The modellers have reached Battle of Britain Day: 15 September. This was the climax of the Battle of Britain, when the RAF threw everything at the massed squadrons of Luftwaffe that were trying to attack London. It was on this day that Douglas Bader's controversial tactic, the Big Wing, was successfully deployed as five squadrons flew together in tight formation. The RAF modellers must try to bring to life a model Big Wing, getting all of their planes in the sky at once and flying in formation before their final dogfight with the model Luftwaffe. It's Luftwaffe squadron leader Jurgen's birthday, and he spends it contending with failing engines, rogue pilots and fog.