After a collision with a comet, a nearly 8km wide piece of the asteroid "Orpheus" is heading towards Earth. If it hits, it will cause an incredible catastrophe that will probably extinguish mankind. To stop the meteor, NASA wants to use the illegal nuclear weapon satellite "Hercules," but discovers soon that it doesn't have enough firepower. Their only chance to save the world is to join forces with the USSR, which has also launched such an illegal satellite. But will both governments agree?

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.