The plot begins with a flashback after the first film where Lawrence Gordon, played by Cary Elwes, crawls from the bathroom to search for help after being forced to cut off his own foot. On the way, he finds a steam pipe and utilizes it to cauterize his cut leg. At present day, Ryan and Brad awaken in a store window in a shopping mall in front of an audience while their wrist is tied to a worktable. Facing them is a saw and their mutual love interest, Dina, who is raised on top of a third one. Jigsaw's puppet informs them that they have to make a choice between their lives or Dina's life. After contemplating for a bit and realizing Dina's disloyalty, Ryan and Brad decide to save themselves, which drops Dina into a buzz saw and eventually killing her.
After Mark Hoffman survives from the end of the last Saw installment, Jill Tuck visits Matt Gibson, an internal affairs officer at Hoffman's detention branch, and offers to incriminate Hoffman in exchange for immunity and law enforcement protection. Meanwhile, Hoffman continues to kill innocent people until Jill is surrendered to him. He sends videos to the internal affairs detective, Gibson, and offers hidden messages regarding his whereabouts. The detective eventually figures out Hoffman's location and sends in a unit to kill him. Unfortunately, their efforts are of no avail when the entire team is killed through a gas chamber.