Lurk (Frankie Howerd), the last of a long line of cowards, is boot-boy at Twithampton House when war is declared. The servants, headed by Groping the sex mad butler - are marshaled to volunteer by heir apparent Nigel Phipps-Fortescue (Jonathan Cecil). Only Lurk rejects the call to arms but a twist of fate finds him hypnotised into believing he alone can save England and joins up hastily. While serving under Sergeant Major Groping (Bill Fraser) in France, Lurk is tricked into no man's land where he stumbles across Nigel, eventually finding their way behind enemy lines and stealing the Hun's master war plan. Hotly pursued by Von Gutz (Lance Percival), Nigel is left with no choice but to tattoo the war plans onto Lurk's unconscious buttocks - a terrible cheek! Making their way back to England, Lurk's rear is in hot demand as the treacherous Von Gutz, fiendishly disguised as a doctor, tries to get his hands on it.