Deborah and Charles, young executives at the thriving Pontifex Advertising Agency, are very much in love. Deborah is recognised by her employers as the most brilliant TV executive in the country, while Charles is regarded as 'thoroughly reliable'. But there is one hard-and-fast rule at the agency: the board of directors will not allow any married women on their staff; as soon as a girl marries, she must resign!

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.

Lilli Marlene, a French girl working as a bar maid in her uncle's café in Benghazi, Libya, turns out to be the girl that the popular German wartime song Lili Marleen had been written for before the war, so both the British and the Germans try to use her for propaganda purposes - especially as it turns out that she can sing as well. When the Germans kidnap her in Cairo and she starts appearing in radio broadcasts from Berlin, her British soldier friends think that she's joined the enemy. They couldn't be more wrong, because after the war it turns out that her songs over the radio contained secret messages to London from British agents in Berlin.

There's pandemonium in a country house when various relatives come to stay.