After a successful exercise in camouflage, Mainwaring delivers a lecture on communications. Apparently, the four main targets are the Gasometer, the railway bridge, the telephone exchange and the reservoir. They are vital to the town's survival, so two men will be posted at each location. If they see anything suspicious, they will phone Mainwaring via the nearest telephone box. Frazer asks Mainwaring what will happen if the telephone boxes are out of action, and many alternatives are suggested, including a heliograph, tick-tacking, Shooting a hole in the top of the Gasometer and setting fire to it, and tapping the railway line and laying your ear onto it (Pike dismisses this idea by telling Jones that a train may come and run over your ear)
Pike and Godfrey admit they do not know how to use a telephone box; Mrs Pike believes they are unhygienic and Godfrey is hopeless with machines. After a hilarious practical demonstration, they march down to the telephone box nearest the reservoir. Pike is the first to get the lesson, but the recipient of the call is Mrs Pike, who gives Mainwaring and Wilson an earful. When a queue begins to form, Walker cons them into believing that telephone calls are going on ration from tomorrow!
That evening, while out on patrol, Frazer and Walker spot a plane crash into the reservoir. Walker phones Mainwaring, then mysteriously vanishes. Mainwaring and the rest of the platoon arrive, and their verbal attempts to persuade the Germans to surrender results in heavy gunfire. Mainwaring tells Jones to phone GHQ, but Jones' muddleheadedness results in him ringing the Plaza Cinema instead, and ends up believing that Googie Withers and Eric Portman are aboard the plane. He gets no joy from emergency services either, so the ARP Warden helps Jones get through.
Eventually, Lieutenant Hope-Bruce of the Coldstream Guards arrives and tells Mainwaring that they've surrounded the reservoir. He pompously tries to get Mainwaring to leave the situation in the hands of the regular army, but is quick to cancel an order for mortar bombs under Mainwaring's persuasion. Walker returns and tells Mainwaring that he's talked to the man in charge of the reservoir: he has opened the sluices, and the Germans will have to swim for it in less than two hours. Laughing, Mainwaring says they should leave the mopping up to the Coldstream Guards.
|Arthur Lowe||Captain Mainwaring|
|John Le Mesurier||Sergeant Wilson|
|Clive Dunn||Lance Corporal Jones|
|John Laurie||Private Frazer|
|James Beck||Private Walker|
|Arnold Ridley||Private Godfrey|
|Ian Lavender||Private Pike|
|Janet Davies||Mrs Pike|
|Bill Pertwee||ARP Warden Hodges|
|Avril Angers||Telephone Operator|
|Timothy Carlton||Lieutenant Hope-Bruce|
|Stanley McGeagh||Sergeant Waller|
|Pamela Cundell, |
|Ladies in the Queue|
|Richard Jacques||Mr Cheesewright|
|Colin Daniels and |