Photographer Adam Stanheight awakens in a dilapidated bathtub, with his ankle chained to a pipe. Across the room is oncologist Dr. Lawrence Gordon with the corpse of an apparent suicide victim between them holding a revolver and a microcassette recorder. Both men find a tape in their pockets, and Adam retrieves the recorder. Adam's tape urges him to escape, while Gordon's tells him to kill Adam by six o'clock or his wife Alison and daughter Diana will be killed. Adam finds a bag containing two hacksaws inside the toilet which they try to use to cut through their chains, but Adam's saw breaks. Gordon realizes the saws are meant for their feet, and identifies their captor as the Jigsaw Killer—a serial killer testing his victims' will to survive through murderous contraptions referred to as "games", whom Gordon knows of because he was once a suspect.