A young man named Adam wakes to find himself chained to a rusty pipe inside a decrepit subterranean chamber. Chained to the opposite side of the room is another bewildered captive, Dr. Lawrence Gordon. Between them is a dead man lying in a pool of blood, holding a .38 in his hand.
Neither man knows why he has been abducted, but instructions left on a microcassette order Dr. Gordon to kill Adam within eight hours. If he fails to do so, then both men will die; Dr. Gordon's wife, Alison, and his daughter will also be killed.
Recalling a recent murder investigation by a police detective named Tapp, Dr. Gordon realizes he and Adam are the next victims of a psychopathic genius known only as "Jigsaw." With only a few hours left to spare, they must unravel the elaborate puzzle of their fate in the midst of mounting terror. The killer has provided them with only a few clues and two handsaws--too weak to break their steel shackles, but strong enough to cut through flesh and bone.