Even eager Lance Corporal Jones runs out of loyal patriotism as Captain Mainwaring keeps mishandling his lovingly spotlessly kept butchers' van. The vital mission 'to provide directions to a real Army convoy' is looking ever bleaker as Mainwaring keeps issuing idiotic orders instead of listening (in time) to better ideas from Wilson or even Pike. Passers-by like Hodges, the verger and the vicar's seniors club celebrating Mr. Blewitt's birthday, all suffer from plans B, C, D and so on. This only makes the crossroads the van is stuck at look like a bombed area and the convoy unreachable.

Despite Wilson and Frazer's warnings, Mainwaring accepts to enlist local newspaper journalist Cheeseman as 'temporary' private. The very next phone call requires literal covering-up too: Pike's head is stuck in a gate. When German bombs knock out railway, water and gas supplies, the captain declares martial law, overruling all civil authorities. His rule under draconian penalties extends even to bath permits. Lifting it may take an act of God - or HQ.

Mainwaring complains about a man's 'sissy' appearance and luggage during a briefing on a training mission. He'll play a secret agent to be guarded anonymously, while HQ sends equally secret counter agents to identify and catch him. So all civilians are mistrusted or ignored, including a military experiment researcher's warning for an escaped gorilla. The (fake) ape certainly makes a monkey of the verger and the warden, who are determined to betray the platoon. The battle of daft wits continues.

As part of Walmington's patriotic effort to finance a Spitfire, the platoon practices Morris (spring fertility) dancing. It's sissy to Scotsman Frazer's taste, except wielding the whiffling stick like a club, which upsets Jones. His nerves suffer because his sweetheart, lively widow Mrs. Fox, now accepts attention from old town clerk Gordon. At Jones' request the captain is going to talk to her. Alas that starts new suspicions. Things worsen when Fox auditions for the part of Lady Godiva, in fleshings, which stirs jealousy from the platoon's ladies.

Captain George Mainwaring is delighted when widowed Lady Maltby offers his Home Guard platoon first choice, over Mr. Hodges's A.R.P. Wardens, for the use of her Rolls Royce while she can't get rationed petrol anyway. Its first appearance would be the high-profile visit of a French general who will pin up decorations. To jealous snob Mainwaring's green envy, his bright but unassertive sergeant Arthur Wilson, a warmly greeted relative of the lady who doesn't even notice his name or rank, is also asked by H.Q. to write and deliver the welcome speech for the general, as he alone masters French. To turn it into a proper staff car, the Rolls must be camouflaged; on the way to the paint shop the lady's driver runs out of petrol at the town hall, so he calls and Frank drags uncle Arthur along with petrol 'commandeered' from Hodges's sidecar. The captain believes them unable and sends the platoon to tow the Rolls; Frazer smells a profit in doing the paint job for less in his funeral establishment, but from then on things go spectacularly wrong...

When Jones accidentally kills a turkey, the platoon organises a lavish turkey dinner for the pensioners of Walmington-on-Sea.