The people of Walmington-On-Sea are becoming apathetic about the war effort. When practicing on a firing range, Mainwaring is told to keep the noise down and Hodges is verbally assaulted for his efforts as chief warden.

Mainwaring decides to scare his townfolk by getting the platoon to dress up as fifth columnists and marching through the countryside 'asking ze questions!' Will their plan work? Or will Mainwaring just end up looking rather silly infront of Captain Square and the Eastgate platoon?