After "The Poseidon Adventure", in which the ship got flipped over by a tidal wave, the ship drifts bottom-up in the sea. While the passengers are still on board waiting to be rescued, two rivaling salvage parties enter the ship on search for money, gold and a small amount of plutonium.

A police detective's violent nature keeps him from being a good cop.

Hooker and Gondorf pull a con on Macalinski, an especially nasty mob boss with the help of Veronica, a new grifter. They convince this new victim that Hooker is a somewhat dull boxer who is tired of taking dives for Gondorf. There is a ringer. Lonigan, their victim from the first movie, is setting them up to take the fall.