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. 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. This war will be fought on land and sea and in the air, but it will also be fought on the airwaves. Relying on first-hand accounts from Reginald Jones as well as papers recently released by the Admiralty, this fills a huge missing piece in the canon of World War II literature.