William J. Stuart, art director of a New York advertising agency, on a Florida Gulf vacation, finds trouble in coffin-size lots when his inoffensive hobby of shell collecting introduces him to Valerie. She in turn, with her interchangeable stories, introduces him to the police, crooked politicians on the lam, murder and danger. Not able to get out from under, Bill tags along with her, and with a shell for a clue, loses his faint heart in tangling with the criminals. Free for all fun.