When Adam (Leigh Whannell) is jolted back to consciousness after nearly drowning at the bottom of a decrepit bathtub, he awakes to find himself chained to a rusty pipe inside a dark torture chamber. There is someone else in the room. Dr. Lawrence Gordon (Cary Elwes) has also just regained consciousness and is chained to the opposite side of the space. Between them a man is lying in a pool of blood after apparently shooting himself in the head with the pistol in his hand. Adam and Dr. Gordon piece together the clues left behind by the deranged criminal mind that has brought them together and finally realize that they, too, must make a seemingly impossible set of choices for their lives.