Walker and Godfrey become trapped in the gasworks they are guarding. Mainwaring and his men come to the rescue with watery consequences.

The War Office plans a review of both the Home Guard and the ARP in order to decide which less fit soldiers of the first and less fit of the second should be transferred to the other corps. As this is the last thing that either group's men want, various tricks go towards making them look younger or older. After a field exercise proves the platoon's fitness is at best questionable, Mainwaring tries a terrible toupee, Wilson wears a corset, Frazer and Walker make money by using unsuitable beautician substances.

The platoon are at the cinema watching a Greta Garbo film but only Mainwaring stands to attention for the National Anthem and gets knocked over by the others rushing for the exit. On the bus home they encounter Hodges, who is rude to the bus conductress. Mainwaring defends her but again gets knocked down as the men hurry to get off for last orders. After getting the men to stand for the anthem on parade next day - though Wilson accidentally plays the German anthem - Mainwaring falls out with his wife and has a toasted cheese supper with Wilson and Jones. He falls asleep in his air raid shelter and dreams that he is Napoleon, Wilson is Wellington and the conductress is Josephine. As in the events of the previous night he gets knocked over. When he wakes up his wife has left him a note to tell him off for not coming home.

Rumours abound when Sergeant Wilson is seen with his arm around an attractive young woman in a WREN's uniform, causing an argument between himself and Mainwaring who catches him sleeping off a hangover in the church hall. Suddenly pigeons appear - Walker has got them to sell to Jones in the absence of other meat but he has yet to kill them, which he eventually does. However, a radio report reveals the disappearance of pigeons from Trafalgar Square, so he hides them in the organ loft and out they fly when Jones plays the organ. The young lady with Wilson is actually his daughter from a brief marriage.

The platoon are on an exercise whereby everyone except for Godfrey and Jones ends up in a deserted barn. Jones sees from the map that they have been given the wrong reference and the barn will be blown up in half an hour as part of a live ammunition exercise. They try to phone up but Godfrey cuts the wire by mistake. To add to their plight Jones's van has broken down,so he has to take the colonel's car to reach the barn and warn the platoon in time.

After another of Mainwaring's long, creative 'vital' lectures, Jock is appointed spokesman to complain that the men have had enough of wasting their time. Mainwaring tries a suggestion from the manual: the troublemaker is to have a go at being an officer. 'Captain' James Frazer proves an even worse tyrant, demotes and promotes but impresses the new area commander, fellow Scotsman Major General Menzies. When everyone is back to their real rank, an invitation arrives, meant for Jock, who didn't mention the charade. The invite is to play the pipes with some men in the HQ haggis ceremony.

The platoon's first-ever private party, thrown by the captain at his disappointingly plain home, proves un-amusing. It's cut short anyhow by a bomb alert - a hit on his bank! The money is carried to the church, counted painstakingly with typical bumbling and tension then carried off, but the captain drives the horse cart with new disastrous consequences.

The Walmington-on-Sea platoon are called in to help with the harvest at Godfrey's ladyfriend's farm.

Jones has been entrusted with five hundred pounds by local shopkeepers but when he brings it to the bank he finds he has a pound of sausages instead. Frazer hypnotizes him into recalling when he last saw the money, apparently stuffing a chicken for Mr. Blewitt, but there is no money in the chicken. various suggestions as to its whereabouts are made until it is eventually found.

At a business community function, where both Wilson and Walker outshine him, Captain Mainwaring accepts a challenge to prove his men are a match for the Home Guard's new, regularly trained, physically superior commandos. Their display of 'brains over brawn' should eliminate the commandos-guarded fuel depot by getting a fake bomb there. A far-fetched plan, dressed up as firemen, ends in the usual brave bumbling from the braves and the for once collaborating verger. Surprises come from a real fire and real brains.

Captain Square ridicules Mainwaring for the pitiful state of some of his men's rifles. The captain rudely denies it but internally blames it all on Wilson's lax inspection techniques and general poor style. Worse is to come when the A.R.P. have George Mainwaring formally charged for an un-obscured light emanating from the church where his platoon is. The verger warns Hodges it's a false accusation and the platoon rehearses their lie. Mainwaring defends himself and the presiding magistrate is none other than the still offended Square.

In 1941 the War office decides to test an experimental invention for delivering explosives. For secrecy the test is done on the coast, using three local Home Guard platoons. Mainwaring's vanity is used to make him volunteer blindly for 'special duties', which turn out to be the dirty work. However the weapon gets away, following Frank's illegal home-made radio, and only the bumbling bunch is in a position to stop it blowing up all Walmington on Sea.

The platoon is called to seize a German pilot, who got stuck parachute-jumped on the bomb-damaged church hall tower clock. Getting him down is hard enough, given the language barrier. Then Jones manages to drop the ladder, the warden refuses to help. Even the clock's hourly knighthood fight display figures seems to remember it's German-made. Luckily, the vicar listened to fairy tales as well as Wilson.