Tipped off by Frazer and Godfrey, Capt. Mainwaring and Sgt. Wilson investigate a house from where they believe someone may have been signalling to enemy aircraft. They take the suspect back to the church hall, but chaos ensues when an incendiary bomb comes through the roof and the platoon desperately battles the blaze. (Gold recreates three episodes of Dad's Army that haven't been seen on television since they were first broadcast in 1969.)