In the fourth of the highly successful Frankie and Annette beach party movies, a motorcycle gang led by Eric Von Zipper kidnaps singing star Sugar Kane managed by Bullets, who hires sky-diving surfers Steve and Bonnie from Big Drop for a publicity stunt. With the usual gang of kids and a mermaid named Lorelei.

Local beach-goers find that their beach has been taken over by a businessman training a stable of body builders.

A Martian teenager sent to prepare for an invasion falls in love with an Earth girl.

A millionaire sets out to prove his theory that his pet chimpanzee is as intelligent as the teenagers who hang out on the local beach, where he is intending to build a retirement home.

An astronaut goes into space with a chimpanzee. When they return to Earth after their orbit, it is discovered that the chimp has the brains of the astronaut, and the astronaut has the brains of the chimp. Complications ensue.