Following Jigsaw's grisly demise, Mark Hoffman, the final apprentice to the serial killer is deigned a hero. Meanwhile, Agent Strahm is tested and puts the pieces together. While Strahm realizes that Hoffman is helping Jigsaw, five seemingly unconnected people face a horrible lesson about teamwork.
Strahm follows all the leads he can get off Hoffman, including the death of his sister and why he joined Jigsaw. Hoffman and Strahm circle each other until it boils down to a gruesome and bone-crushing finale.