Just when audiences thought they'd heard the last of the demented killer Jigsaw Saw IV renaisses his trap-filled legacy, this time targeting the last remaining officer who touched the case, SWAT Commander Rigg. As FBI agents Strahm and Perez begin to dig through the remains of Jigsaw's crime-scene hideout a new puzzle presents itself with Rigg as the pawn in another deadly game filled with moral quandaries and torture-filled traps. At stake are the lives of his superior officer Hoffman and his friend and fellow cop Eric Matthews, whose abduction by the dead Jigsaw triggers an obsession in Rigg that will haunt him 'til the grisly end.