Captain George Mainwaring has a difficult assignment. To whip a group of eccentric and lazy middle-aged men into somewhat decent soldiers for the Home Guard to prepare for a potential German invasion. But it's 1944, and with invasion becoming increasingly unlikely, Mainwaring's Home Guard unit uses its free time to come up with ways to entertain themselves. That all changes when an attractive journalist arrives in Walmington-on-Sea, and word comes from MI5 that a German spy is in the village. Mainwaring's unit now has the chance to prove their worth to the war effort.