Exhausted by the relentless German air attack, the RAF pilots and ground crews are stretched to their limits. The crew in the Pit have devised a novel approach to level the field, but a critical error turns the weight of the Luftwaffe against the cities and innocent civilians. Can the RAF respond? Can Lieutenant Carlisle overcome her own guilt and efforts to oust her from MI6 over this costly mistake? Can they hide the secret technology that can turn the tide of the Battle of Britain?