A group of sorority sisters try to cover up the death of their house-sister after a prank gone wrong, only to be stalked by a serial killer.

Between the events of 'Saw' and 'Saw II', a sick and desperate John Kramer travels to Mexico for a risky and experimental medical procedure in hopes of a miracle cure for his cancer, only to discover the entire operation is a scam to defraud the most vulnerable. Armed with a newfound purpose, the infamous serial killer returns to his work, turning the tables on the con artists in his signature visceral way through devious, deranged, and ingenious traps.

Bodies are turning up around the city, each having met a uniquely gruesome demise. As the investigation proceeds, evidence points to one suspect: John Kramer, the man known as Jigsaw, who has been dead for ten years.

After a sudden underwater tremor sets free scores of the prehistoric man-eating fish, an unlikely group of strangers must band together to stop themselves from becoming fish food for the area's new razor-toothed residents.