The story unfolds as photographer Adam Faulkner (Leigh Whannell) awakens in a chilling scenario—submerged in a bathtub filled with water. In a desperate attempt to escape, he inadvertently pulls the drain plug, and a peculiar glowing blue object swirls down the drain, quickly vanishing from sight. As his cries echo in the dark, it becomes clear that he is not alone. The somber and tense atmosphere reveals Dr. Lawrence Gordon (Cary Elwes) who is trapped in the same grimy industrial bathroom, sparking the flickering lights with the flip of a switch.
Both men are shackled to opposing corners of the room, their eyes drawn to a lifeless figure sprawled in a pool of crimson, clutching a revolver and a microcassette recorder. As the plot thickens, they uncover envelopes in their pockets, each containing chilling microtapes—what they initially perceive as instruments of their doom. The voice on Adam's tape chillingly questions, "Are you going to watch yourself die, or do something about it?" Meanwhile, Lawrence's tape bears a sinister ultimatum: he must kill Adam before the clock strikes six, or risk watching his wife and child meet a grisly fate, leaving him to suffer an agonizing death alone in this forsaken place. "Let the game begin..." the voice ominously concludes, setting a dark tone for their desperate plight.
Soon, they stumble upon hacksaws hidden in the toilet tank; however, their intended use is deceptive. While Adam's frustration leads him to break one, Dr. Gordon recognizes the harsh reality—these saws are his only tools for escape, intended to free them from their shackles by slicing through their own ankles. A series of flashbacks introduces the sordid history of their captor, known as the "Jigsaw Killer," characterized by gruesome tests that have claimed previous victims, like Paul and Mark, each left bearing pieces of skin removed in the shape of puzzle pieces.
As tension mounts, Gordon contemplates the ethics of their situation. He realizes that the Jigsaw Killer does not directly enact death upon his victims, but rather forces them into agonizing choices. Flashbacks reveal the aftermath of one survivor’s test, Amanda Young (Shawnee Smith), a shattered heroin addict who believes her harrowing experience has forged her into a stronger person.
The narrative quickly shifts, and viewers are presented with past moments from Dr. Gordon's life—his heartfelt times with his family juxtaposed against his current torment. Meanwhile, Detective Tapp (Danny Glover), alongside his partner, investigates the Jigsaw case. Their ill-fated attempts to apprehend the killer only deepen the tragedy, culminating in Tapp's intense obsession that leads him to surveil Dr. Gordon, convinced of his guilt.
As the stakes rise, Gordon uncovers a box filled with ominous items—a cigarette, a lighter, and a dark suggestion to kill Adam by contaminating the cigarette with the blood of the deceased. ### They devise a desperate plan to outsmart their captor by simulating a death, but their attempts backfire horrifically as a powerful electric shock courses through Adam's chain, revealing the grim reality—he is still alive.
In a shocking turn of events, the film culminates in a frantic finale—the arrival of Zep, a pawn of the Jigsaw Killer, who is intent on fulfilling the sinister rules imposed upon him. Tensions boil over as alliances are tested, leading to a heartbreaking shootout that decimates the lives caught in this intricate web of horror and revenge.
In the film's climax, the identity of the true Jigsaw killer is startlingly unveiled—John Kramer (Tobin Bell), once a patient of Dr. Gordon. He reveals the haunting truth that the key to Adam's shackles was all along in the bathtub, the very object that disappeared in the film's opening moments. Faced with the chilling reality of his fate, Adam reaches for John's gun, but is met with a shocking retaliation. In a final, haunting farewell, John voices the words, "Most people are so ungrateful to be alive. But not you. Not anymore." As he seals Adam's fate with the door, the film crescendos to its chilling conclusion, leaving audiences with Adam's anguished screams of despair echoing through the credits.
