Summer 1939. War is coming. The British believe that, through ingenuity and scientific prowess, they alone have a war-winning weapon: radar. They are wrong. The Germans have it too. They believe that their unique maritime history means their pilots have no need of navigational aids. Flying above the clouds they, like the seafarers of old, had the stars to guide them, and that is all that is required. They are wrong. Most of the bombs the RAF will drop in the first years of the war land miles from their target. They also believe that the Germans, without the same naval tradition, will never be able to find targets at night. They are, again, wrong. In 1939 the Germans don’t just have radar to spot planes entering their airspace, they have radio beams to guide their own planes into enemy airspace. War is coming, and it is to be a different kind of war.