Captain Mainwaring is told that he can promote one of the privates in the platoon to lance-corporal and he chooses Frazer as being the most efficient. Unfortunately this leads to a bitter rivalry between Frazer - who keeps dishing out charge sheets and becomes unpopular - and Jones, culminating in a fight between the pair of them, and ultimately Mainwaring has to return Frazer to the ranks.

When Private Walker gets his call-up papers to join the regular army it comes as a shock to the platoon because he is useful to them for his black market activities. Wilson is chairing a committee and tries to get him turned down whilst Jones has him jumping off a ladder barefoot to induce flat feet. Ultimately he does get turned down because he is allergic to corned beef.

Whilst on fire-watching duty the platoon see a man shining a torch. He speaks with a European accent and has a dog called Fritz and they arrest him as an enemy agent. However, the man - Sigmund Murphy - tells them that he is a British subject and even helps them put out a fire in the church hall, after which Hodges explains that Sigmund is indeed a British citizen and the husband of his Auntie Ethel.