Mainwaring recently sent a letter to GHQ requesting the platoon's use of the local lighthouse as a guard house, and has just received permission to do so.
Walker is unable to attend because he is delivering some essential supplies, but the Lewis gun has been fixed, no questions asked.
Suddenly, they hear a large moaning sound, and they realise they have turned the main lamp on, lighting up the whole town.
Walker arrives with the Lewis Gun, and Hodges suggests shooting it out, but Mainwaring says it will kill the men in the lighthouse.
Walker suggests asking a friend of his at the power company to black out the entire county, but Mainwaring rebuffs the suggestion as it will draw too much attention, so instead they decide to put the nearby transformer out of action via the fuses, but only succeed in fusing the whole of the Jolly Roger Pier, but not the lighthouse.
Walker talks to her and convinces her to reconnect the line, as the two of them used to work together during his pre-war smuggling activities.
However, they are taking a long time about it and Hodges soon hears the sound of German bombers approaching.