Two men, Dr. Lawrence Gordon and photographer Adam Stanheight, awaken chained at opposite ends of a filthy, abandoned bathroom. Between them lies a dead man holding a gun and a tape recorder. Both discover tapes in their pockets, which, when played, deliver a chilling message from a sadistic serial killer known as Jigsaw. The killer's twisted game assigns Dr. Gordon the task of killing Adam by a certain time, or else his wife and daughter will be murdered. The two captives must piece together the puzzle of their connection to each other and the elusive murderer whose signature strategy involves placing victims in deadly contraptions that force them to inflict terrible choices upon themselves in a bid for survival.

As the desperate men struggle to escape their shackle's and the clock ticks towards their deadline, flashes of backstory reveal the killer's M.O. and his previous victims. A parallel storyline follows a veteran detective named David Tapp, whose obsession with the Jigsaw case has caused his partner's death and his own disgrace. Tapp believes that Dr. Gordon is the key to unraveling the mystery, as he surveils him obsessively. Dread and tension mount as both the captives and the detective race against time to connect the dots before the killer claims his next victims, and the true nature of the fiend's perverse games becomes apparent.