In 1935 a simple demonstration in the Midlands of the reflection of radio waves from an overflying aircraft led to the development of a war-winning device - radar. This volume tells the story of a team of mainly young scientists and engineers who played a vital part in enabling Britain to outwit the onslaught of the Nazi bombers during World War II. It reveals how they fought the radar war-within-a-war, providing solutions to each new threat posed by the enemy. They were civilians working strictly under the Official Secrets Act for the whole of their wartime service. But ordinary civilians they were not; nor was the team they made up anything other than extraordinary in its combined brain power, its continual need for improvisation and its outright dedication to the changing needs of the services at home and overseas. This team was known successively by a number of titles until in November 1940 it acquired and retained the name by which it was best known throughout the war: TRE - the Telecommunications Research Establishment.