A U.S. sailor docks in London and in three days tries to save his brother from the gallows.

Tony Hudson offers his young wife Jane a cruise on a yacht as a honeymoon trip. Although Jane suffers from chronic seasickness, she accepts and one day they go on board the Turtle, a fine yacht owned by an industrialist friend, Dudley Partridge. A lot of misadventures await them before they finally reach France.

Gormless 25 year-old Cardew, wealthy beneficiary of the Robinson Will, should have left St. Fanny's School many years ago. However, seedy headmaster Dr. Jankers (music hall favourite Fred Emney) is in the toils of shady bookmaker Harry the Scar (boxer Freddie Mills) and has so-far kept his golden goose perched firmly at the bottom of the class. Blissfully unaware of nefarious intrigue around him, Cardew continues to flirt coyly with the French mistress and gamble for school dinners on the form room roulette wheel. But canny Scots solicitor McTavish has been sent to investigate... Featuring television's Billy Bunter, Gerald Campion, gorgeous Vera Day, Will Hay cohort Claude Hulbert, muddle-mouthed Stanley Unwin, a young Ronnie Corbett, and enough old jokes to fill a Christmas Cracker factory.