The film starts with Seth in the pendulum trap. It is revealed Seth is a murderer who was released early from prison due to a technicality. Seth is told by Jigsaw's puppet that if he wants to live he has to destroy the things he has used to kill-his hands.The trap is later revealed to be unwinnable, but Seth is made to believe that the aim of the trap is for him to push buttons inside of two devices which would crush both of his hands before a bladed pendulum (intended to slice him in half) descends upon him. Seth had in fact, crushed his hands, but as the trap is unwinnable, the Pendulum does not stop. From the side of the room, somebody watches Seth getting sliced in half through a Peep hole.
Meanwhile, Agent Strahm shoots Jeff and enters the room where Jigsaw died. After investigating and finding Jigsaw's corpse, the door is locked on Strahm by Hoffman. Strahm finds a hidden door in the room and kicks it open. The outlines of the door had been painted with glow in the dark paint, only visible in the dark. The door leads down a new hallway. Strahm finds a tape recorder and plays it. Jigsaw's voice addresses him on the recording and warns him not to proceed, but to stay where he is, stating that he can find salvation or let his "insatiable hunger to uncover the truth drive (him) deeper in the abyss." Jigsaw urges him to make the right choice. Strahm disregards the warning and leaves the room, walking down the hallway. He is soon attacked by a figure in a pig mask, presumably Hoffman. He wakes to find himself in one of Jigsaw's traps. His head is in a sealed box, which quickly starts to fill with water. Before he runs out of air, he performs a tracheotomy with the tube of a ballpoint pen in order to breathe. The police make it to the Gideon warehouse, and Hoffman emerges carrying Corbett, claiming that he saved her. Strahm is carried out on a stretcher, still alive, but badly injured.