The Beach Party Gang meets a coterie of muscle-men who try to take over their spot on the beach in Muscle Beach Party. Surfing sensations Frankie (Frankie Avalon) and Dee Dee (Annette Funicello) have their security threatened when Flex Martian (Rock Stevens) and a collection of well-oiled weight-lifters invade their turf. While tensions heat up on the beach, wealthy contessa Julie (Luciana Paluzzi) arranges for her business manager S.Z. Matts (Buddy Hackett) to entice Flex into becoming the latest in her long line of boyfriends. Julie's feelings change when she meets Frankie, who, honored by Julie's amorous attentions, returns her affections, causing a rift not only between Dee Dee and himself, but a further collapse in relations between the surfers and the body-builders, which is assuaged only by the music of Dick Dale and the Del Tones and Little Stevie Wonder.