In the spring of 1944, German forces work to secure intelligence about the upcoming Allied invasion, after one of their spies is intercepted in London by MI5 agents, Major Cunningham and Captain Meeks. Meanwhile, Captain Mainwaring finds his Home Guard in the coastal town of Walmington-on-Sea suffer from a lack of appreciation for their work in contributing to the war effort. Things change when the platoon, during an exercise, accidentally force Rose Winters, an elegant journalist, off the road. When they learn she intends to write a report about them for a national magazine, the men feel delighted, but also are charmed by her presences, causing them to have feuds with the townsfolk, and especially with their wives. The matter is further complicated when Sergeant Wilson develops a friendship with Winters after recognising as a student he once tutored at the University of Oxford.