Bumbling policeman P.C. Josser is dismissed from the force after a disastrous attempt to distinguish himself at a nightclub. Mistaking his own comrades for criminals, he inadvertently "bowls them over like nine-pins," leading to his immediate firing. After losing his job, Josser sets himself up as a private detective. He is hired by a young lady who owns a racehorse and needs protection for her "favourite" horse before a big race. To protect the animal, Josser goes undercover as a stableman. Despite his efforts, the horse is drugged, leading to further comedic mishaps as he attempts to solve the case and redeem his reputation.

Charting the military escapades of serial bungler Tommy Josser, Josser in the Army sees the hapless hero in France during wartime, where he masquerades as a German general, unmasks a spy, gets captured and then makes a spectacular airborne escape!