Catalina Caper is a 1967 musical/beach party/crime movie directed by Lee Sholem.
In a museum overlooking a beachfront, a man named Lawrence sneaks through an elaborate art collection and steals an ancient scroll.
The next day, Charlie Moss and Don Pringle arrive in California after finishing their university classes in Arizona. Charlie is bringing Don to visit Catalina Island, as Don has spent his entire life in the desert setting. While on the ferry to Catalina, Don becomes enamored with a dark-haired girl staring off into the ocean. Don attempts to get to know her better, but Charlie takes him aside with some other teenagers and they dance to a performance by Little Richard.
Eventually, the ship arrives at Catalina Island. As Charlie disembarks, three girls immediately approach him in a romantic fashion. Don watches the dark-haired girl leave in the arms of another man. Lawrence departs and presents a cane to Arthur Duval, his employer. The two depart, unaware that they are being observed by a thin man in a grey suit.
Lawrence and Arthur board a boat in the harbor. Arthur has come to Catalina with his wife Anne and their son Tad. Tad does not know that his parents hired Lawrence to steal the scroll, but he is aware that they have been involved in operating confidence schemes in the past. Their current plan is to have Anne make a copy of the scroll, then sell the copy to a wealthy Greek man named Lakopolous. Once he has purchased the fake scroll, Lawrence will return the real one back to the museum.
Charlie's sister Tina meets up with Don and her brother, and the three then meet the Duvals and Lawrence. Charlie invites Tad to join them on a scuba diving party, but Tad declines. Charlie, Don, and Tina then go scuba diving near the Duval's yacht. An intimidating man in a scuba suit boards the yacht, claiming to have come to collect the scroll for Mr Lakopolous. A scuffle ensues between Arthur and the scuba diver, and the scroll (stored in a watertight case) falls into the water. The scuba diver attempts to escape, but Don and Charlie see what has happened and try to subdue him. Their efforts are unsuccessful, and the diver gets away.
Don and Charlie board Arthur's yacht along with a member of the Harbor Patrol. Arthur claims the man was after his wallet, and the others accept this explanation. Once they leave, Lawrence voices his concern that they've lost the real scroll, but Arthur says that he's confident they can get it back before Lakopolous sends his divers to retrieve it.
After the excursion, Tina, Don, and Charlie go to a beach party along with Tad. The party atmosphere changes when the dark-haired girl Don saw on the boat appears, enchanting almost every other man on the beach. Tina then attempts to woo Tad in order to make Don jealous. Everyone then heads off the beach to another function, but Don stays behind. As he watches the water, he sees the dark-haired girl calling for help. She has lost her bikini top, and Don gives her his jacket to cover-up with. Upon thanking him, the girl explains that her name is Katrina Corelli.
Don attempts to get her to join the others, but she claims she's waiting for her boyfriend, Angelo. When they encounter Angelo, he is upset to see Katrina with another man, and Don leaves. Katrina asks Angelo what he has been doing, but he dismisses her questions, claiming he should not have brought her to Catalina. This causes Katrina to leave him and return to Don.
Don has joined the others, but when Katrina arrives Tina gets jealous and wanders off. Don explains to his friends what happened with Angelo, and Katrina reveals that Angelo came to Catalina to help a man named Lakopolous, who hired Angelo for his sea-diving abilities. The group then begins to wonder if Angelo may have attacked Tad on his yacht.
Tina is heard crying for help out in the water, but instead of being saved by Don (as she expected), she is rescued by the thin man who had been trailing Lawrence. This leads to every other girl on the beach growing jealous of Katrina, and marching off. The teens soon reconcile on a boat during another musical performance.
Later that day, Arthur and Lawrence propose a scuba contest, promising a $100 reward if they can find the watertight cases at the bottom of the harbor. The gang happily participates, but during the contest Lakopolous' divers (including Angelo) arrive. An underwater struggle occurs, and the divers get away. Arthur finally admits to his son why they're really on Catalina.
Tad, Don, Charlie, and the Harbor Patrolman discuss a plan to catch Angelo and the other man who attempted to assault Arthur. Their plan leads to Angelo being arrested while his accomplice takes off with a container that he believes contains the scroll. The chase finally ends when the thin man with the hat knocks the accomplice into the water. He manages to retrieve the scrollcase and identifies himself as Fingers O'Toole, a private investigator who has been trailing Lawrence and Arthur. He attempts to arrest Arthur, but finds that the scroll is not in the case. With no evidence against Arthur, Fingers must release him.
The real scroll has been taken away by Tad, who returns it to its place in the museum. Back on the island, everyone is dancing down by the docks as Arthur and Anne prepare to change their unscrupulous lifestyle.
- Tommy Kirk as Don Pringle
- Del Moore as Arthur Duval
- Peter Duryea as Tad Duval
- Robert Donner as Fingers O'Toole
- Ulla Strömstedt as Katrina Corelli
- Jim Begg as Lawrence
- Sue Casey as Anne Duval
- Lyle Waggoner as Angelo
- Mike Blodgett as Bob Draper
- James Almanzar as Sid
- Lee Deane as Dino Lakopolous
- Venita Wolf as Tina Moss
- Brian Cutler as Charlie Moss
- Peter Mamakos as Borman
- Musical highlights include Little Richard singing "Scuba Party" (seemingly while under the influence of some mind-altering substance) and The Cascades with "There's a New World Opening for Me." 
- Carol Connors (original name Annette Kleinbard), the singer of "Book of Love", had career highlights before and after this movie. She sang lead for the Phil Spector girl-group The Teddy Bears ("To Know Him Is To Love Him"), and later co-wrote the theme music for Rocky.
- Mary Wells, who sang the theme for the movie ("Never Steal Anything Wet") was one of the first breakout female stars of the Motown label. Her most famous song is the 1964 hit "My Guy".
- Both Never Steal Anything Wet and Scuba Party were titles planned for the film, before the makers decided on Catalina Caper.
- The movie was made by Executive Pictures Corporation, which had been formed by Bond Blackman and Jack Barlett. It started filming in September 1965. Tommy Kirk was signed to a four-picture contract of which this was to be the first (though he did not make any subsequent films with the company).
- Venita Wolf receives an "introducing" credit, though strictly speaking this was not her first movie appearance (she was a bikini girl in The Oscar from the previous year). The somewhat-common perception of such credits being career killers proved to be the case with her, as she only did a handful of TV appearances afterwards.
- The cinematographer was Ted V. Mikels, who would later produce and direct several films used by Mystery Science Theater 3000, RiffTrax, and Cinematic Titanic.
- The opening animated sequence was done by "Murakami Wolf" (later known as merely "Fred Wolf Films"). They previously did the opening sequence for the Woody Allen-dubbed Japanese film What's Up Tiger Lily! and would later be known for producing the 1987 Teenage Mutant Ninja Turtles animated series.
- A 1969 episode of the TV series Dragnet includes a stock footage shot of a movie theater marquee that shows Catalina Caper on a double bill with the Elvis Presley film Speedway (from 1968).