During the autopsy of serial killer Jigsaw (Willem Dafoe), a cassette tape is discovered in his stomach in which he warns that his gory games will continue. Sure enough, SWAT Lt. Dylan Russell (Dulé Hill) is forced to follow a blood-drenched trail of torture, dismemberment and death in order to find two missing colleagues. A pair of FBI profilers follow Riggs, suspecting he might be Jigsaw's accomplice, even as they unlock the puzzle of the killer's origins, seen in gruesome flashbacks.