Harold Gern (Anthony Carbone) is a successful New York businessman in legal trouble. He is on holiday in Puerto Rico with his attractive wife Evelyn (Betsy Jones-Morland). They are joined by Martin Joyce (Edward Wain), Harold’s lawyer. The three take a boat out to do some scuba-diving and when they surface, something has happened to the atmosphere. They can’t breathe without the scuba-tanks. Manuel, the pilot of the boat, is dead from asphyxiation They row to shore and find that they can only breathe in the jungle, as the plants give off oxygen.

Everyone in town is dead and they hear no-one on the radio. They may be the last people on Earth, so Harold takes charge. They live on fish. Harold says they should move north to a colder climate, where there may be other people. Harold feels that Evelyn is his. She and Martin disagree, because she doesn’t love Harold. Evelyn and Martin have an affair and run off, but Harold chases them, kills Martin, and takes possession of Evelyn.

The film was produced and directed by Roger Corman and concentrates on the sensational, though the posters are more lurid than the movie. Robert Towne, the screenplay-writer and Edward Wain, the actor, are the same person. He didn’t finish the script on time, so Corman hired him to play Martin while he finished the script. The music was composed and conducted by Ronald Stein. The movie was released in a double bill with The Little Shop of Horrors, but it was shot together with Creature from the Haunted Sea and Battle of Blood Island to form Corman’s Puerto Rico Trilogy.