The platoon requisitions a boat and sets off to guard the local river. After getting lost in what they think is the English Channel, they believe themselves to be stranded behind enemy lines.

Frazer the undertaker loses the spring of the Lewis gun, He believes it may be in a recently made coffin which is shortly to be buried.

Mainwaring uses Walker's new tracking dog to locate a discarded parachute. After finding dozens of ladies' undergarments made from the parachute's silk, an enemy airman is finally cornered.

When Private Godfrey admits to having been a conscientious objector during the Great War, he is branded a coward, sent home in disgrace and thereafter ostracised by the platoon. When he saves Mainwaring's life, though, and it emerges that he holds the Military Medal for bravery under fire as a medical orderly, he is forgiven and reinstated

The platoon is placed on guard duty, and mans a machine gun post at the end of the pier. When Pike loses the food and the boat, morale begins to fall. The situation worsens when they spot a drifting sea mine.

Mainwaring announces that a dance will be held to raise morale. He is less than pleased when Pike announces that his date for the evening will be the daughter of Mainwaring's cleaning woman.

A runaway barrage balloon must be retrieved. After a series of mistakes, Mainwaring is dragged through the countryside by one of the balloon's cables.

The platoon is given a heavy naval artillery piece but the town's bandstand, a rare example of Victorian ironwork, stands in its field of fire. The town council insists it must be preserved but Mainwaring reasons that a demonstration of the gun's capabilities will quiet any protests.

General headquarters determines that Mainwaring has never held a commission, and he is demoted to private. Wilson temporarily leads the platoon while Mainwaring attempts to regain his command.

The bank takes a direct hit during an air-raid, but the bomb fails to explode, leaving Mainwaring and Wilson stuck in the vault with it. When the bomb disposal officer leaves to collect the right tools, the platoon members take matters into their own hands.

The platoon's supply of ammunition is used up when engaging a low-flying German plane, and Mainwaring sets up a court of inquiry to determine who should be held responsible. The inquiry descends into farce when the platoon attempts to re-enact the event.

Mainwaring teaches the men to use the public telephone system as emergency communication. Jones and Hodges attempt to phone general headquarters when a German aeroplane crashes in the reservoir.

The platoon is selected to attend a weekend camp run by a tough Spanish captain.

Jones donates his van as a troop transport, but Walker wants to use it for his black market activities. Both men are sent with the van to work with Air Raid Precautions during an exercise.