Godfrey and Walker are trapped when a bomb falls on the local pumping station. When the rest of platoon tries to free them, they all become trapped. A pipe bursts and the room begins rapidly filling with water.
The older members of the platoon try to make themselves look younger to avoid transfer to the ARP.
Mainwaring, unhappy because his men are not living up to his expectations and believing his leadership to be unappreciated, dreams he is Napoleon after eating too much toasted cheese.
Wilson goes AWOL and is seen with his arm round a younger woman, who turns out be his daughter. Walker acquires 250 pigeons for Jones to sell as off-the-ration meat. When Jones then hears of an unexplained shortage of pigeons in Trafalgar Square, he changes his mind.
A misread map leads the platoon to a barn marked as a target for artillery practice. Jones and Godfrey try to stop the firing by 'phoning, but Godfrey cuts the wire. Jones must reach the barn before it is blown up.
After Frazer complains that Mainwaring is wasting his time with irrelevant lectures, Mainwaring allows Frazer to act as captain for a couple of days. Frazer begins abusing his power.
To boost morale, Mainwaring holds a party in his home. A bomb hits the bank during the party; thousands of pounds must be counted and guarded by the party guests, then taken to the Eastgate branch by horse and cart.
Private Godfrey requests leave to help a widowed friend gather the harvest and Mainwaring, citing the harvest as vital to the war effort, offers the assistance of the platoon.
When Jones arrives at the bank to deposit £500 from local shopkeepers for the servicemen's canteen, he realises his packet contains half a pound of sausages instead of the money.
The platoon is challenged to plant a dummy bomb in the officer commanding's office. They disguise themselves as firemen travelling in an old fire engine, but Hodges spots a real fire.
Mainwaring is charged with showing a light and taken to court by a gleeful Hodges. When Mr Yeatman tries to correct Hodges, he is blackmailed into remaining silent.
Operation Catherine Wheel is the testing of the War Office's new, radio-controlled explosive wheel. The platoon is chosen for fatigues, but Pike and Walker sneak off to listen to the radio, unknowingly pushing the wheel out of control.
An enemy pilot has bailed out and is trapped on the town hall clock. The platoon climbs up the precarious ladder to reach him, but getting down becomes more difficult when Jones breaks the ladder.
