Law enforcement finds itself chasing the ghost of a man dead for over a decade, embroiled in a diabolical new game that's only just begun.

Each year the population of sleepy Lake Victoria, Arizona explodes from 5,000 to 50,000 residents for the annual Spring Break celebration. But then, an earthquake opens an underwater chasm, releasing an enormous swarm of ancient Piranha that have been dormant for thousands of years, now with a taste for human flesh. This year, there's something more to worry about than the usual hangovers and complaints from locals, a new type of terror is about to be cut loose on Lake Victoria.

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.

Working in the shadow of an esteemed police veteran, brash Detective Ezekiel “Zeke” Banks and his rookie partner take charge of a grisly investigation into murders that are eerily reminiscent of the city’s gruesome past. Unwittingly entrapped in a deepening mystery, Zeke finds himself at the center of the killer’s morbid game.