Shecky Moskowitz, a deservedly struggling young comedian, lands a menial job on a cruise ship as the Miss-Universe contest is being held on-board. The Big Man On Deck for this voyage is Dickie Diamond, the ship's comedian and all-around ladies' man. As an assorted array of thugs, Panamanian mercenaries and terrorists try to storm the ship, Shecky hopes for one big chance to prove himself and enter the exciting world of cruise ship comedy.

A sunken US supply ship off a Caribbean island resort is the focus for a series of mysterious piranha attacks. Investigating the death of one of her son's companions after a scuba-diving trip, Anne Kimbrough breaks into the morgue with holidaymaker Tyler Sherman, only to discover that the fish have wings and can fly. But the hotel manager refuses to call off the annual fish fry on the beach, with inevitable consequences...