Set between the events of Saw and Saw II, we see how the sick and desperate John heads to Mexico to undergo an experimental treatment in the hope of being cured of his cancer diagnosed as fatal. The process is sold as something very risky and expensive, but he feels that he has nothing to lose. However, he will realize the error of his ways seeing how the entire operation is a fraud to exploit those in the most vulnerable position. Now he has nothing to lose, and John, full of rage, sets out towards a new and dark purpose, resuming his work as a serial killer to give the scammers what they deserve. Under the incisive gaze of Jigsaw, these tricksters will find themselves trapped in a visceral and ruthless game full of ingenious, devious and deadly traps.