This is a complete recap of all eight entries in the Saw film series.
Adam Stanheight, a photographer, awakens in a bathtub in a large dilapidated bathroom and finds himself chained at the ankle to a pipe. Lawrence Gordon, an oncologist, is similarly shackled across the room and between them is a corpse holding a revolver and a microcassette recorder. Each man has a tape in his pocket and Adam is able to retrieve the recorder. Adam's tape urges him to escape the bathroom, while Lawrence's tape tells him to kill Adam by six o'clock, or his wife and daughter will be killed and he will be left to die in the bathroom. Adam finds a bag containing two hacksaws inside a toilet tank. They attempt to cut through the chains, but Adam's saw breaks and he throws it at the mirror in frustration, revealing a hidden camera behind the mirror. Lawrence realizes that the hacksaws are meant to cut off their feet and identifies their captor as the Jigsaw Killer, whom Lawrence knows of because he himself had been a suspect five months before.
Flashbacks show that while Lawrence was discussing the terminal brain cancer of a patient, identified as John by an orderly named Zep Hindle, with his medical students, he was approached by Detective David Tapp and Detective Steven Sing, who found his penlight at the scene of a Jigsaw "game", of which at least three have been investigated. Lawrence's alibi clears him, but he reluctantly agrees to view the testimony of the only known survivor, a heroin addict named Amanda Young, who believes Jigsaw has helped her by forcing her to play one of his games.
Meanwhile, Alison and Diana Gordon are being held captive in their home by Zep Hindle, who is watching Adam and Lawrence through a camera behind a two-way mirror in the bathroom. The house is simultaneously being watched by David Tapp, who has been discharged from the force. Flashbacks show that Tapp became obsessed with the Jigsaw case after hearing Amanda's testimony and was eventually able to locate Jigsaw's hideout in an abandoned mannequin factory. He and Sing entered the building, where they apprehended Jigsaw and saved a man from another trap, but Jigsaw escaped after non-fatally slashing Tapp's throat. Moments later, Sing was killed by a shotgun trap while pursuing the killer. Convinced that Lawrence was Jigsaw, Tapp began to stalk him after his discharge.
In the bathroom, Lawrence finds a box containing a lighter, two cigarettes and a one-way cellphone. He then recalls his abduction: he was trying to use his phone after being trapped in a parking garage and was suddenly attacked by a mysterious pig-masked figure. Adam and Lawrence try to use a cigarette dipped in the corpse's blood, which is in fact cyanide, to stage Adam's death, but the plan fails when Adam receives an electric shock through his ankle chain. Adam then remembers his own abduction: he was in his photo development room when the power went out and, after finding a mechanical ventriloquist puppet in his living room, was attacked by a similar pig-masked figure. At gunpoint, Alison calls Lawrence and tells him not to trust Adam, who subsequently admits that he was being paid to take photos of Lawrence, many of which were in the same bag as the hacksaws. Adam also reveals his knowledge of Lawrence's affair with one of his medical students. Lawrence had been with her before he was abducted. Lawrence realizes from Adam's description that the man who hired him was David Tapp. Shortly afterwards, Adam finds a photo that he didn't take, showing a man staring out a window of Lawrence's house, whom Lawrence identifies as Zep. Moments later, the clock strikes six.
Meanwhile, Alison, who managed to free herself, is forced by Zep to call her husband one last time to inform him about his failure. Thereby, she fights with Zep for the gun. The struggle attracts Tapp's attention, who saves Alison and Diana and chases Zep to the sewers, where he is eventually shot in the chest during a struggle. Lawrence, who only heard gunshots and screams of his family, finally saws off his foot in an act of desperation and shoots Adam with the corpse's revolver. Moment later, Zep enters the bathroom to kill Lawrence, stating that "It's the rules", but Adam, who suffered only a flesh wound, overpowers Zep and bludgeons him to death with the lid of the toilet tank. As Lawrence crawls out of the room to find help, Adam searches Zep's body for a key and finds another microcassette recorder, which reveals that Zep was another victim, following the rules of his own game to obtain an antidote for a slow-acting poison in his body. As the tape ends, the "corpse" in the middle of the room rises and is revealed to be Lawrence's patient, John Kramer, the real Jigsaw Killer. He tells Adam that the key to the chain is in the bathtub. The key however had been drained when Adam initially awoke. In desperation, Adam tries to shoot John but is paralyzed by another electric shock. Afterwards, John turns off the lights in the room and seals the door, leaving Adam to die in the bathroom with the words "Game Over".
Several months after the events in the bathroom, police informant Michael Marks awakens in a room with a spike-filled mask locked to his neck. A video tape informs him that in order to unlock the device, he must cut into his eye to obtain the key, which has been surgically implanted and sealed behind it. As the timer starts to count down, Michael finds a scalpel, but cannot bring himself to cut out his eye and is killed after 60 seconds when the mask closes on his head.
At the scene of Michael's game, Detective Allison Kerry finds a message for her former partner, Detective Eric Matthews, and calls him in. Despite not wanting to be involved with the case, already dealing with a divorce and the subsequent estrangement from his son, Daniel, Eric reluctantly joins Kerry and a SWAT team led by Sergeant Daniel Rigg to the factory, which had produced the metal parts used for the construction of Michael's trap. Upon their arrival, they quickly find and apprehend John Kramer, who is severely weakened by his cancer disease. John however had already planned his apprehension and had prepared another game. He shows the detectives several computer monitors showing eight people trapped in a house. Among them are Amanda Young, the only known survivor, and Eric's son, Daniel. A nerve agent filling the house will kill them within the next two hours, but John assures Eric that he'll see his son again unharmed if he followed the rules of his own game and simply sat down and talked to John until the timer went off. At Kerry's urging, Eric agrees in order to buy time for the tech team to arrive and trace the video signal.
The victims in the house are informed by microcassette recorder that several antidotes for the nerve gas are hidden all around the house. One is in a large safe in the room where they woke up, and a cryptic clue is provided. One of the prisoners, Xavier Chavez ignores a warning note left by Jigsaw and uses a key on the rooms door, which activates a booby trap and causes a bullet to be fired through the peephole, thereby killing another prisoner named Gus Colyard. The remaining prisoners search the house for more antidotes after being able to leave the room, with no success. Obi Tate, who had assisted Jigsaw in abducting the others, is forced to crawl into a furnace to obtain two antidotes inside, but inadvertently activates the furnace and is burned alive before the others can save him, destroying the antidotes. In the next room, Xavier throws Amanda into a syringe-filled pit to look for a key, instead of going into the pit himself. Even though she is able to retrieve the key, Xavier is unable to unlock the next door to a room with another antidote before the timer expires and therefore leaves the group. Throughout the game, the prisoners discuss possible connections between them and find out that each one of them has been jailed before, except for Daniel.
Meanwhile, John Kramer passes the time with both idle and cryptic chat, eventually telling Eric that his survival of a suicide attempt after his cancer diagnosis is the true reason for his games. With the little time left to him, he wants to help others to appreciate their lives by forcing them to fight for it. Eric, not interested in any of this, runs out of patience and returns to the monitors. He destroys several of John's documents and sketches at Kerry's suggestion in order to provoke John, but fails. As the tech team arrives moments later, John reveals the connection between the eight victims to Eric. Eric had innocently framed all of them for various crimes they didn't commit.
In the house, Xavier returns to the safe room and finds a colored number on the back of Gus' neck. After realizing the answer to the clue from the first tape, he kills Jonas Singer, another prisoner, with a spiked bat to get his number. Afterwards, he begins to hunt down the other prisoners. Meanwhile, Laura Hunter succumbs to the nerve agent after finding the clue revealing Daniel's identity and his connection with Eric. Therefore, Amanda and Addison Corday, the last prisoner, abandon him. Amanda however returns immediately afterwards after finding the corpse of Jonas. Meanwhile, Addison finds a glass box housing another antidote, but her arms get trapped in the arm holes which are lined with hidden blades. Moments later, she's found by Xavier. He however is merely interested in her number and leaves her behind after obtaining it. While being pursued by him, Amanda and Daniel find a tunnel in the safe room which leads to the dilapidated bathroom where they find the rotten corpses of Adam Stanheight and Zep Hindle. Daniel eventually collapses, just before Xavier finds them. Amanda notes that he can't read his own number, telling him that he needed her help to get it. To her shock, Xavier cuts the skin from his neck and then approaches her and Daniel. Embracing his opportunity, Daniel, who feigned his collapse, jumps up and slashes his neck with a hacksaw, killing him.
Having witnesses Xavier's pursuit of his son on the monitors, Eric brutally assaults John and forces him to lead him to the house, to which John eventually agrees. The area in which John had talked to Eric is revealed to be an elevator, which they use to leave the factory. Meanwhile, the tech team tracks the video's source and Sergeant Rigg leads his team to the address, where they find VCRs playing previously recorded footage of the game in the house. As Kerry realizes the game had already been over at the time they found John, the timer expires and a large safe opens, revealing Daniel, who was trapped inside with a sufficient amount of oxygen. Meanwhile, Eric enters the real house alone and eventually finds the bathroom, where he is attacked and subdued by a pig-masked figure. Shortly afterwards, he awakens shackled at the ankle to a pipe. An audio tape left by Amanda reveals that she had merely pretended to be another victim and has in fact become John Kramer's apprentice after surviving her first test. Furthermore, she intends to continue John's work after his death. When the tape ends, Amanda appears in the doorway and seals the door, leaving Eric to die with the words "Game Over". Outside, John hears Eric's screams and happily smiles, despite his severe injuries.
Six months later, the aftermath of abother game is discovered by Rigg and his SWAT team. The victim, Troy, was meant to rip eleven chains from his body in order to escape from a nail bomb. After securing the crime scene, Rigg calls Detective Mark Hoffman and Detective Kerry. Kerry, who is guilt-ridden over the disappearance of Eric Matthews, points out that the room's only exit door had been welded shut, breaking Jigsaw's modus operandi of giving his victims a chance to survive, as Troy couldn't have escaped the explosion even if he won his game. Later that night, while reviewing a video tape found at the crime scene, Kerry is abducted as well and awakens in a harness that is hooked into her rib cage. She manages to retrieve the key from a suspended beaker filled with acid and unlock the harness before the timer expires. However, her trap had been manipulated as well, causing it to tear apart her rib cage nonetheless, killing her in the process.
Now bedridden from cancer, John Kramer instructs Amanda Young to abduct Dr. Lynn Denlon from the Angel of Mercy Hospital for a last game. After Amanda brought Lynn to John, Lynn is instructed to keep him alive until another victim has completed a series of tests. As John explains the rules, Amanda locks a collar around Lynn's neck, which is connected to John's heart rate monitor and will detonate if he dies or Lynn moves out of range. Meanwhile, the other victim, Jeff, awakens in a box in an abandoned meatpacking plant and learns from a microcassette recorder that he must play one of Jigsaw's games, which will lead him to "the man responsible for the loss of his child". Jeff has become unstable and vengeful in the past three years since his son, Dylan had been killed by a drunk driver, and therefore neglected his wife and his daughter, Corbett.
Jeff's first test leads him into a freezer room, where he finds Danica Scott, the only witness of Dylan's death, who refused to testify in court. She is entirely naked and chained at the wrists between two poles, which begin to spray ice-cold water at her body. Danica manages to convince Jeff to help her, but freezes to death before he can retrieve the key. His second test leads him to a large vat. Chained to the bottom of the vat is Judge Halden, who gave Dylan's killer a light sentence of merely six months in jail. The vat slowly fills with liquefied pig carcasses. Eventually, Jeff reluctantly incinerates Dylan's possessions in order to retrieve the key and successfully saves the judge. In his third test, he finally faces Timothy Young, Dylan's killer, who is strapped to a machine, that will slowly twist his limbs and neck until they break. The key to save him is tied to the trigger of an enclosed shotgun. After struggling with himself, Jeff eventually tries to free Timothy, but taking the key discharges the shotgun and accidentally kills Halden. Ultimately, Jeff is unable to stop the machine before Timothy's neck is broken.
Meanwhile, Lynn performs an improvised surgery on John, during which she removes a piece of his skull to take the pressure from his brain. Thereby, he hallucinates about another woman, Jill Tuck, and declares his love, distressing Amanda, who thinks that his words were meant for Lynn. Flashbacks show the time during which she became John's apprentice, as well as her abduction of Adam Stanheight, which had left her guilt-ridden to the point she gave him a mercy killing some time after his game. In the present, she reads a letter addressed to her which further distresses her and severely worsens her mental state even more. As Lynn confesses to John that her ordeal has given her new appreciation of her family, Amanda returns with the news that Jeff has completed his tests, but refuses to remove Lynn's collar. She reveals that she no longer believes in John's philosophy, telling John that she had been the one who manipulated the traps of Troy and Kerry.
Refusing to listen to John's warnings, Amanda shoots Lynn in the back just as Jeff arrives. He retaliates by shooting Amanda in the neck with a gun he found earlier. As Amanda slowly dies, John reveals that he had tested her as well the entire time. Aware of her manipulations of the games and unwilling to allow a murderer to inherit his legacy, he decided to test "her will to keep someone alive." Therefore, he had told her nothing about Jeff and Lynn, including the fact that they were actually husband and wife. After Amanda's death, John talks to Jeff, offering to call an ambulance for Lynn if he accepts to participate in one final test. He can either choose to kill John or forgive him. Jeff tells Kramer he forgives him, but then slashes his throat with a power saw. Seconds later, the door to the room slams shut as a dying John plays a final tape, which tells Jeff that he has failed his test by killing John. Furthermore, John reveals that his daughter, Corbett, had been abducted as well. In order to save her, Jeff must play another game. The tape ends as John dies, causing Lynn to be killed by her collar.
Following John's death and the discovery of his body, a wax-coated microcassette is found in his stomach during his autopsy. It reveals to Mark Hoffman, the detective called in to hear it, that the games will continue and that he will be tested as well. Elsewhere, two men - Trevor, who has his eyes sewn shut, and Art Blank, who has his mouth sewn shut - awaken in a mausoleum, chained at their necks to a winch. Trevor panics as he can't see anything and thereby activates the winch. Therefore, a brutal fight engages between the men, ultimately ending in Art killing him and successfully freeing himself from the trap.
Four days after Allison Kerry's death, a SWAT team led by Hoffman and Lieutenant Rigg finds her body. Shortly afterwards, the special agents Peter Strahm and Lindsey Perez join the investigation, revealing that Kerry had been their informant. Prior to her death, they had received a message and a key from her. Noting John Kramer and Amanda Young's physical limitations, which would've prevented them from trapping Kerry without help, Strahm states they are looking for another, yet unidentified accomplice. He soon becomes suspicious of Rigg, who has developed an obsession with saving people in the six months since the disappearance of Eric Matthews. Later that night, Rigg is attacked and subdued in his apartment. Upon his awakening, a video tape left by his attacker reveals to him that Eric is still alive and has ninety minutes to save himself, with Hoffman's life also at risk. Meanwhile, Rigg must play his own game in order to face and overcome his obsession. The detectives are shown to be at each end of a large seesaw. Eric is held atop an ice block by a chain noose around his neck, while Hoffman is strapped to a chair with electrodes at his feet. If Eric leaves the ice block or too much of the ice melts, both men will die. Shortly afterwards, another man enters the room where they are trapped and oversees their game.
Meanwhile, Rigg finds a pimp, Brenda, bound to a mechanical chair in his living room. Upon its activation, the trap starts to slowly rip off Brenda's scalp. Rigg successfully frees Brenda, but kills her in self-defense when she attacks Rigg with a knife. Rigg is then led to the Alexander Motel and instructed to abduct the owner, Ivan Landsness, who Rigg finds out is a sadistic serial rapist. He forces Ivan into another trap, which he can only escape by sacrificing both of his eyes. As he can't bring himself to do this, he's eventually dismembered by the trap after 60 seconds. Rigg is then led to his next test at an school, where he finds a married couple, Rex, who is already dead, and Morgan, who had already faced her own test. Rigg then gives her a key he had found earlier and tells her to save herself. Upon leaving the building, Rigg activates the fire alarm to make sure Morgan is found quickly and goes to the location of his final test at the Gideon Meatpacking Plant.
At the same time, Strahm and Perez interrogate Jill Tuck, John Kramer's ex-wife, who tells them about her and John's past. Jill had once been pregnant with a boy to be named Gideon, after John's first construction project during his career as a civil engineer. However, she lost the baby, when Cecil Adams, one of her patients robbed her recovery clinic for drug addicts and thereby accidently injured her, causing her to suffer a miscarriage. The interrogation is suddenly interrupted, when Strahm is informed about the murder of Ivan Landsness. At the motel, the agents learn that the room, where Ivan died, had been rented by a lawyer named Art Blank, the survivor of the mausoleum trap, who had vanished two weeks earlier. Art is revealed to be the man overseeing Eric Matthews and Mark Hoffman in their trap. Later at the school, after learning about the game of Morgan and Rex, the agents find out that all victims of Rigg's game, as well as Jill, were Art Blank's clients. Minutes later, they find a puppet and a tape recorder in another room left by Jigsaw. The tape contains a cryptic message for Perez, according to which her partner would soon "take the life of an innocent man." However, after playing it, the puppet's face suddenly explodes, blowing shrapnel into Perez' face. After Perez is taken to the Saint Eustace Hospital, Strahm furiously interrogates Jill once more, now convinced of Art Blank's involvement in the game, and thereby eventually finds out that Rigg's game is going to end at the Gideon Meatpacking Plant.
Strahm arrives at the plant shortly after Rigg, but ends up following Jeff Denlon instead. After finding Jeff in John Kramer's sickroom, Strahm shoots him in self-defense when Jeff aims a gun at him and demands to know where his daughter is. Meanwhile, Art Blank, who's still in the same room as Hoffman and Eric, pulls out a device from his bag which will free all three of them once the timer expires. If tried to use it earlier, a deadly device strapped to his back would kill him by severing his spine. Moments later, Rigg finds them and is shot by Eric with a gun given to him by Art, as he tries to prevent Rigg from entering the room. While he's injured by the gunshot, Rigg still breaks through the door, causing two large ice blocks to swing down from the ceiling and crush Eric's head, killing him. In return, Rigg shoots and kills Art, believing him to be the one responsible for the game, only to learn from another audio tape, that his interference had caused Eric's death. Hoffman, the actual accomplice, releases himself from the chair and leaves the fatally wounded Rigg behind with the words "Game Over." After that, he goes to the sickroom and closes the door, thereby trapping Strahm inside with the corpses of Jigsaw, Amanda, Jeff and Lynn Denlon. The scene cuts to Hoffman at the morgue, while John's final tape to Hoffman plays once again, revealing that the events of Saw III and Saw IV happened at the same time.
Seth Baxter, a convicted murderer, wakes up chained to a table beneath a large pendulum blade. A videotape informs him that he can release himself by crushing his hands between two vises. He does so, but the blade still swings down and cuts him in half, while someone witnesses his death through a peephole.
In the meatpacking plant, Peter Strahm shoots Jeff Denlon and is locked in the sickroom. Upon examining the room, he discovers a hidden exit door and a microcassette recorder. The urges him to stay in the sickroom. However, he ignores Jigsaw's warning and proceeds through the secret hallway, where he is suddenly attacked and subdued by a pig-masked figure. He wakes up agan with his head sealed in a box, which quickly fills with water, but survives by performing a tracheotomy with a pen from his pocket. Meanwhile, Detective Hoffman leaves the building with Corbett Denlon, stating that they are the only survivors. Therefore, he is shocked when Strahm is brought out alive as well.
During a press conference, Hoffman is promoted and credited for his efforts in ending the Jigsaw murders. After the conference, he finds an anonymous note in his office that reads "I know who you are". Shortly afterwards, he learns of Lindsey Perez' death. Upon visiting Strahm at the hospital, the latter tells Hoffman that Perez's last words had been "Detective Hoffman" and questions how he escaped the plant. Strahm is also visited by his supervisor, Special Agent Dan Erickson, who puts him on medical leave. Suspicious of Hoffman and determined to uncover the truth about his involvement with Jigsaw, Strahm continues his research on his own.
Meanwhile, in an underground room, five people wake up with collars around their necks. The keys to these collars are located in glass boxes across the room. A videotape informs them, that all five of them are connected. Mallick, a drug addicts, activates the trap's timer and everyone reaches their keys in time, except for Ashley, a former fire inspector, who is decapitated when the collars retract and pull her into a mounted razor blade. In the next room, they learn that several jars hanging from the ceiling, contain keys to three bomb shelters. Charles, an investigative journalist, strikes Mallick with a metal rod, thinking that one of them inevitably had to die, and begins smashing the jars one by one. Brit, a real estate developer, and Luba Gibbs, a city planner, each find a key to the shelters. However, before going to safety, Luba saves Mallick's life by striking Charles from behind. While Luba, Brit and Mallick enter the shelters in time, Charles is killed by several nail bombs. In the third room, five short cables must be connected to a full bathtub in the middle of the room to close five circuits and thereby unlock the next door. Luba attacks Mallick to use his body to close the circuits, but Brit kills her and they use her body instead. In the fourth room, they find a machine fitted with circular saws and a beaker, which has to be filled with ten pints of blood in order to open the next door. Mallick notes the five armholes and they realize that all five of them were meant to survive the game by working together. Brit also works out their connection. They were all involved in a case of arson which had resulted in the death of eight people. With no other options, Brit and Mallick shove their arms into the saw blades in order to fill the beaker.
Meanwhile, Strahm learns that Seth Baxter was the murderer of Hoffman's sister, Angelina Acomb, and had been released from prison on a technicality, despite having received a life sentence. In an act of revenge, Hoffman had abducted and killed Seth in a trap to make the murder appear to be another one of Jigsaw's crimes. Therefore, he was later abducted by John Kramer, who blackmailed Hoffman into working with him. They set up most of the games from the previous films together. Strahm's activities soon attract the suspicion of Agent Erickson, which is further fueled when Jill Tuck claims Strahm is stalking her. After Hoffman calls Erickson to tell him about Strahm's theory of a second accomplice, Erickson puts a tracker on Strahm's phone.
Erickson follows the tracker to the observation room of the latest game and finds the phone planted there by Hoffman. He also finds Brit, who has managed to escape from the fourth room after Mallick had passed out from blood loss. Erickson calls for medical attention for the victims and puts out an all-points bulletin on Strahm. At the same time, Strahm follows Hoffman to the renovated nerve gas house from Saw II and thereby finds an underground room containing a glass coffin filled with broken shards. A tape left for him by Hoffman urges Strahm to enter the coffin. Strahm stops the tape, when he hears Hoffman coming closer. After a brief struggle, he seals Hoffman in the coffin. Moments later, the room of the door slams shut. When Strahm asked Hoffman how to open it, Hoffman points to the tape. Upon listening to the rest of the message, Strahm is informed that if he does not enter the coffin, he will die and everyone would suspect him as Jigsaw's successor. The coffin is slowly lowered into a hole in the floor, while the walls close in on Strahm and ultimately crush him to death.
Simone and Eddie, two predatory lenders, awaken on either side of a room split by a caged-in scale, wearing helmets with screws poised to pierce their temples. The one who sacrifices the bigger weight of flesh will survive. Eddie cuts fat from his torso, but Simone chops off her arm and Eddie is killed when the timer expires. As he reviews the game's footage, Detective Lieutenant Mark Hoffman is called to the scene by Dan Erickson, who has found Peter Strahm's fingerprints. Also present is Lindsey Perez, whose survival was covered up by Erickson for her protection. They learn from Dr. Adam Heffner, the coroner who performed all of the autopsies for the case thus far, that the knife used to cut the jigsaw piece from Eddie's flesh was only used once before, on Seth Baxter. The agents intend to find the videotape from the crime scene of Seth Baxter's death to prove Strahm's involvement.
While at the hospital to meet with Simone, Hoffman is met by reporter Pamela Jenkins, who claims to have found something at the meatpacking plant, where John Kramer and Amanda Young had died. He later meets with Jill Tuck at her clinic and takes control of the next game and is given five envelopes from the box left to her after John's death, each containing photos of people to be tested. After he leaves, a flashback reveals that Kramer brought Amanda Young to Jill, who had deemed her a lost cause, as proof of his methods. A later flashback, as Jill delivers a package from the box to the hospital, shows that Jill met with Kramer at the plant hours before his death, where he gave her the box's key and his promise that she would be protected once the games were over.
William Easton, an insurance executive for Umbrella Health, meets with Debbie, the company's attorney, to talk about one his clients, Harold Abbott, who had succumbed to a heart disease after his coverage request had been denied due to an application discrepancy. Hoffman abducts William from his office later that night and takes him to the abandoned Rowan Zoological Institute, where he and his janitor, Hank, awaken in two big vises designed to tighten around their torsos each time they breathe into oxygen masks strapped to their faces. A recording of John Kramer appears on a TV and informs William that he has one hour to complete four tests and remove four bombs strapped to his limbs, or he will lose his family. Hank, a heavy smoker, is unable to hold his breath for long and is killed by the vise. William's other tests force him to save his workers from traps, including a hanging room, a steam room and a carousel. It is shown via flashbacks that John had met William at the opening of Jill's clinic and took issue with his formula. After his cancer was diagnosed, John's coverage request for an experimental Norwegian treatment was rejected by William.
Meanwhile, William's game is watched by a woman named Tara and her son, Brent, from a cage, which contains a tank of hydrofluoric acid and a switch marked with the words "Live" and "Die". Pamela Jenkins awakens in another cage on the other side of the room. During the game, Hoffman is called by Erickson and Perez, who found the Baxter videotape and are having it unscrambled by an offsite technician. They inform him that abnormalities were found in Strahm's fingerprints and Erickson eventually reveals their knowledge of Strahm's death. The moment his voice is unscrambled, Hoffman attacks and kills everyone in the technical lab, plants fingerprints using Strahm's severed hand and sets the room on fire to destroy the evidence.
He returns to the observation room and finds the letter he'd written to Amanda in Saw III, in which he used his knowledge of her role in Jill's miscarriage to blackmail her into killing Lynn Denlon. A copy of the letter had been found by Pamela and given to Jill, who uses it to ambush Hoffman at the same time as William reaches the end of his path with one second left, finding himself between the cages. It is revealed that Pamela is his sister, while Tara and Brent are Harold Abbott's widow and son. Tara is informed by a videotape of John that she can either kill William or free him by using the switch. When she is unable to make a decision, Brent angrily shifts the switch and a bed of needles swings down and injects William's body with the acid from the tank, killing him. Meanwhile, Jill straps Hoffman to a chair and locks a new Reverse Beartrap to his head. She shows him the sixth envelope from the box left to her, which contains his photo, and leaves him without a key. Hoffman however escapes by breaking his hand and jamming the trap. When it activates, He successfully pulls his head out of the trap, thereby ripping open his cheek.
At an unknown point of time, two men, Brad and Ryan, wake up in a metropolitan storefront window, bound at the wrists to opposite sides of a worktable with a circular saw in front of each of them. Their mutual lover, Dina, is suspended above a third saw. As the scene draws attention and police officers arrive, Jigsaw's puppet informs the men that they can kill either each other or let Dina die. They initially fight each other, during which Brad is injured, but ultimately choose to allow Dina to die instead.
Back in the present timeline, right after the events of Saw VI, Jill Tuck meets Matt Gibson, an internal affairs officer working in the same precinct as Detective Hoffman. She incriminates Hoffman and reveals his true identity in exchange for protection and immunity from prosecution. Gibson, who has distrusted Hoffman ever since he saved his life by gunning down a homeless man, agrees to her terms. Meanwhile, Hoffman abducts a group of four racist skinheads - Evan, Dan, Jake and Kara - and places them in a trap at a junkyards, resulting in the deaths of all four of them. Afterwards, he leaves the Reverse Beartrap from Saw VI at the scene to incriminate Jill, who is later put into protective custody. After a meeting of several Jigsaw survivors, including Lawrence Gordon from the first film, Hoffman abducts Bobby Dagen, a self-help guru who achieved fame and fortune by falsifying his own survival story. He sends Gibson some videos with cryptic clues to the game's location, offering him to end the game if Jill is given to him.
Shortly afterwards, Bobby awakens in a cage in an abandoned asylum and is told that his wife, Joyce will die if he doesn't save her within one hour. Joyce is chained at the neck to a metal platform that gradually pulls her down as she watches Bobby's progress. After he escapes the cage, which dangles over a floor of spikes, he begins searching for Joyce. Along the way, he finds Nina, his publicist, Suzanne, his lawyer, and Cale, his best friend and co-conspirator, who have all been trapped as well. However, despite all his efforts, he isn't able to save any of them. After facing his tests, Bobby eventually finds Joyce and is forced to reenact the trap he claimed to survive in his book: he must pierce two hooks through his pectoral muscles and hoist himself up to the ceiling to connect two cords to deactivate Joyce's trap. He fails nonetheless and is forced to watch as a brazen bull capsule closes around Joyce and slowly burns her alive.
Gibson eventually discovers the game's location and sends out a SWAT team, which is sealed in another room in the asylum and killed by toxic gas. Simultaneously, Gibson and two officers infiltrate Hoffman's command center at the junkyard, where they find Dan's corpse sitting in front of several monitors connected to the police headquarter's security cameras. He sees Hoffman brought into the morgue in a body bag and tries to warn his colleagues, but an automatic turret gun rises up and kills him along with his men. Meanwhile, Hoffman kills the coroner and numerous police officers in his path to Jill, who briefly escapes before she is caught and knocked unconscious. He straps her to a chair and locks a Reverse Beartrap onto her head. She awakens as the timer starts and is killed when the trap activates and tears her face apart.
After killing Jill and destroying his hideout, Hoffman is attacked and subdued by three pig-masked figures, one of whom is Lawrence Gordon. Flashbacks show that John Kramer had found him unconscious outside the bathroom of the first film and Gordon has assisted him ever since. This was known only by Jill, who delivered a package to him at the hospital, which had contained a videotape in which Kramer asked him to watch over Jill and take action if anything happened to her. To this end, Gordon has Hoffman brought to the bathroom and shackled by the ankle to a pipe. Gordon appears one final time, throws the hacksaw, which he had once used to cut his own foot, out of the room and then turns off the lights. Finally, he seals the door, leaving Hoffman to die.
A criminal named Edgar Munsen manages to evade police and is pursued onto a rooftop, where he activates a triggering mechanism. He is shot and severely injured by police detective Halloran and his fellow officers.
Elsewhere, five people are held captive inside of a room in a run-down barn, each with a metal noose around their neck leading to a wall of buzzsaws. A taped recording from John Kramer explains that in order to escape, they must give a sacrifice of blood and will eventually need to confess their past sins. The chain nooses begin to pull them towards the saw blades. Four manage to survive by offering blood via purposely cutting themselves on the saws, though one man who was still unconscious during the message and only woke up moments before the ending of the game appears to die. The next test reveals that one of the group-members, Carly, inadvertently caused the death of an asthmatic woman by stealing her purse, which had her emergency inhaler inside. A trio of syringes are revealed - one contains an antidote for a poison in her system, another a saline solution and the third a potent acid. She must inject one into herself in order to save the rest from being hanged. Eventually, volatile group-member Ryan stabs all three into her to save himself, thereby partially melting Carly's face and killing her.
During the games, Halloran and his partner, Detective Keith Hunt, begin to investigate the matter, especially with the discovery of bodies that appear to belong to the unnamed man and Carly, who were both killed in the barn. Halloran becomes suspicious of forensic pathologists Logan Nelson and Eleanor Bonneville. In turn, Logan, a military veteran and former doctor whose wife was killed two years prior, is suspicious of Halloran's motives. Meanwhile, Edgar Munsen is kidnapped from the hospital by an unseen assailant. When the police captain orders John Kramer's grave be exhumed, Munsen's body is found inside.
In another room of the barn, Ryan tries to cheat by escaping through a door marked "No Exit" and his leg is trapped by razor-sharp wires, immobilizing him. Fellow group members Anna and Mitch discover an unlocked door leading into a grain silo, but are quickly trapped inside. A taped message explains that Anna and Mitch will be buried in grain and then killed by falling debris unless Ryan pulls a lever that will free him from the wires around his leg. Ryan eventually agrees, but upon pulling the lever, his leg is instantly severed, though Anna and Mitch survive. Mitch is tested next. A taped message reveals that he sold a motorcycle with a faulty brake to a young man, revealed to be John Kramer's innocent nephew, which resulted in his death in an automobile accident. Mitch will be lowered into a spiral-shaped blade, unless he can reach for a brake lever. However, he is unable to complete the task and is subsequently killed, with his body being shredded.
Logan and Eleanor speak in a bar about their distrust of Halloran, before Eleanor takes Logan to her "studio", revealing that she is an obsessive fangirl of the "Jigsaw Killer" and has built replicas of many of his previous traps, which she worries could incriminate her. Detective Hunt has followed them and informs Halloran about the studio. Halloran orders the two to be arrested, though Logan is able to convince Hunt, an old friend from the military, that Halloran is actually the one to blame, given his past dealings with Edgar Munsen. Logan and Eleanor depart for the barn after Eleanor is able to deduce the location of the game. Halloran manages to pursue them.
In the barn, Anna tries to cheat and slip through a doorway to freedom, only to be captured. She awakens with a gravely wounded Ryan, each chained up in a room with a hooded figure. The hooded figure removes his robe to reveal himself as John Kramer. John reveals that Anna, an old neighbor of his, suffocated her infant child in a fit of rage and threw the blame on her husband by planting the body next to him while he slept. Her husband later committed suicide in a fit of grief, thinking he accidentally smothered his own baby. John explains that the two have not yet earned their survival and have gotten his message "backwards." He places a loaded gun between them, telling them it is the "key" to their survival. Anna misinterprets John's message and attempts to shoot Ryan, only for the gun, which is revealed to be rigged, to backfire and kill her. Ryan begins to cry upon realizing that keys to their chains were hidden inside of the gun and destroyed when Anna pulled the trigger.
While Logan and Eleanor investigate the barn, they are ambushed by Halloran. Eleanor escapes and while pursuing her, Halloran is drugged and knocked-out by an unseen assailant. Logan and Halloran both awaken inside of collars rigged with laser cutters. They are told that they must confess all of their sins or else they will die. Additionally, they have to choose who will face the test first. Halloran forces Logan to go first. Logan confesses that he made a mistake and mislabeled John Kramer's X-Rays, which caused his cancer to go un-diagnosed until it was too late. Despite confessing, Logan appears to die. Halloran confesses at the last second, admitting that he has allowed criminals and murderers to walk free for personal gain.
Suddenly, Logan stands up, stating that he faked his death in order to get Halloran to confess, and reveals that the barn game took place ten years in the past. He was the unnamed man who appeared to die in the first game of the barn trap, but because he was unconscious when the first message was delivered, John Kramer saved him, feeling Logan should not die due to an error. John subsequently took Logan on as his apprentice. The bodies that were found were actually the bodies of criminals that Halloran allowed to walk free, and they were placed into the same tests that Logan was meant to face ten years prior. Logan also reveals that Munsen, one of the criminals Halloran let go, was responsible for murdering his wife. However, because Halloran refused to confess all of his sins and selfishly broke the rules and forced Logan to go first, he will die and be framed as the new Jigsaw killer. Logan tells Halloran that he "speaks for the dead" and reactivates the laser-collar around his neck. Logan slams the door as Halloran's head is sliced apart, killing him.