Muscle Beach Party (1964) was the second of seven official American International Pictures-produced "Beach Party" movies. (The others were: Beach Party , Bikini Beach, Pajama Party , Beach Blanket Bingo, and How to Stuff a Wild Bikini ). Muscle Beach Party is about average, with various strengths and weaknesses. AIP hadn't quite solidified the format yet, though they were well on their way. The first one, Beach Party, spent way too much time following grown-up stars Bob Cummings and Dorothy Malone. Muscle Beach Party is more Frankie and Annette-centric, but it's also the one Beach Party movie without Harvey Lembeck's Eric Von Zipper character, the kids' regular nemesis. Like most of the films it goes on too long - they'd each benefit from about 20 minutes worth of trimming - and the songs in this one are mostly weak, though Muscle Beach Party offers an outstanding performance by newcomer "Little" Stevie Wonder.
Muscle Beach Party has more of a straightforward plot and sentiment than usual, with much of the story revolving around a love triangle between Frankie (Frankie Avalon), girlfriend Dee Dee (Annette Funicello), and a bored Italian Contessa, Juliana Giotto-Borgini (Luciana Paluzzi), a widow in the market for a new husband. Arriving by yacht, anchored just offshore from the kids' beach house, she intends to marry bodybuilder Flex Martin (Mission: Impossible's Peter Lupus, billed here as "Rock Stevens"), whose impressive physique she spotted in a magazine. Through "The Rich Business Manager" (how Buddy Hackett's character is identified in the credits; in the movie he's called S.Z. Matts) handling her affairs, she plans not only to buy up Flex's contract, but also the burgeoning bodybuilding concern co-owned by excitable Jack Fanny (Don Rickles) and a mysterious silent partner, Mr. Strangdour, the strongest man in the world.