hacksaws inside the toilet. Both men try to saw through their chains, but Adam's saw breaks. Gordon realizes that the saws are intended for their feet, and identifies their captor as the Jigsaw Killer, a serial killer testing his victims' will to survive through lethal traps referred to as "games", whom Gordon knows of because he was once a suspect. Five months prior, Gordon, while discussing the terminal brain cancer of patient John Kramer, was interrogated by Detectives David Tapp and Steven Sing, who found his penlight at the scene of one of Jigsaw's games. Gordon's alibi cleared him, but he agreed to view the testimony of heroin addict Amanda Young, the only known survivor of one of Jigsaw's traps, who had been forced to kill and disembowel a man to obtain a key to free herself. After Gordon's release, Tapp and Sing find Jigsaw's warehouse using the videotape from Amanda's game. There, they apprehend Jigsaw and save a man from a trap, but Jigsaw injures Tapp and escapes. Sing pursues Jigsaw down a hallway where he accidentally triggers a shotgun trap and is killed. In the present, Alison and Diana are held captive at their apartment as their captor watches Adam and Gordon through a hidden camera. The house is simultaneously watched by Tapp who, after being discharged from the police following Sing's death, has become obsessed with the Jigsaw case, and remains convinced that Gordon is the killer. Meanwhile, Gordon finds a box containing two cigarettes, a lighter, and a one-way cellphone. He recounts his abduction in a parking garage by a pig-masked figure. Adam recalls his own abduction when he returned home to find a puppet in his darkroom, where he stored photos of Gordon. Alison, held at gunpoint, calls her husband and warns him not to believe Adam. Adam admits to Gordon that he was paid by Tapp to spy on him, and reveals his knowledge of Gordon's affair with one of his medical students whom he had visited the night he was abducted; Gordon deduces that the affair is the reason why he is being tested. Adam finds a photo of Alison and Diana's captor whom Gordon identifies as Zep Hindle, a hospital orderly. Once the clock strikes six, Zep, seeing that Gordon has still not killed Adam, moves to murder Alison and Diana, but Alison frees herself and fights him. The struggle attracts Tapp's