Gerald Clamson (Jerry Lewis) is a bank examiner who loves fishing on his annual two week holiday. Unfortunately one day at the ocean he reels in an injured gangster in a scuba diving suit named Syd Valentine (also played by Lewis). Syd tells Gerald about diamonds he has stolen from the other gangsters and hands him a map. Gerald escapes as frogmen from a yacht machine gun the b...While fishing on a San Diego beach, Gerald Clamson catches ... a sea diver! Even more weird, the "fish" resembles him. The man, who is not (yet) dead, reveals his secret to the peaceful ...