Following the surrender of France in 1940, Nazi Germany begins to plan the invasion of Great Britain - for which it needs complete air superiority. Thus, the Luftwaffe is launched on a collision course with Fighter Command of the RAF, a conflict that will lead to the Battle of Britain, the first truly decisive battle of World War II. Flying a Messerschmitt 109 is Lieutenant Max Bayley, son of flying ace Mark Bayley and his aristocratic German wife - and already, at the age of twenty-one, one of the Luftwaffe's leading pilots. He is well aware that flying a Spitfire for Fighter Command is his older half-brother, John, son of Mark and an Englishwoman. When Max joined up, he had had no concept that Germany and England would ever go to war, and now, however much he secretly regrets his decision, he remains loyal to his comrades: like most German airmen, he has little understanding of the true depravity of the Nazi regime. The dramatic story follows adventures of the brothers, both in the air and on the ground, often close to each other but never actually meeting until the climactic last battle.