Gallico ended his blockbuster novel The Poseidon Adventure with the sinking of the overturned luxury ship as a scant handful of survivors looked on. After the success of the first film of the same name (which ended with the ship still afloat) he was approached by Irwin Allen to write a sequel following on from the film's ending, rather than that of the novel. Mr. Gallico obliged with this further adventure featuring survivors and salvagers, a Communist killer, a beautiful girl pirate, a Vietnam veteran and a New York cop - the stricken Poseidon becomes a battle ground and the prize is a fortune in looted gold.