The crew of a small cargo boat boards a capsized passenger liner and discovers a salvage team has already arrived on the scene. The two parties initially pool their resources to search for survivors and loot the vessel - but the salvagers are not who they appear to be. Disaster movie sequel, starring Michael Caine, Telly Savalas, Sally Field and Karl Malden.

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.