This book concerns an extraordinary story about a German officer who made it seem that he was able to reveal some exceptional data about new weapons under development by the German industry during the war. During the battle for El Alamein in North Africa in November 1942, Hauptmann (Captain) Herbert Peter Cleff, aged 31, was made prisoner of war by the English forces. When captured, Cleff held the title of "Technischer Verwaltungsrat" which may be understood to be a Technical Staff Officer. As he stated to be recently flown in directly from Stalingrad, the intelligence services were keen to learn about the fighting that was raging around that city in Russia.

He was taken to the Middle East branch of the "Combined Services Detailed Interrogation Centre (CSDIC, ME)" where it was discovered that he was an expert in tank engineering. In repeated interrogations he had suggested that he had knowledge of secret weapons under development. This generated the motivation to transfer Cleff to Great Britain so more information could be obtained by MI10 (Military Intelligence). Housed in a requisitioned country estate Cleff appeared have knowledge about projects in the field of a new type of fuel, development of submarine propulsion, long range rockets, jet engines and supersonic flight. After he had decided to collaborate "in order to bring the war and the Nazi regime to an earlier end", he was released and served as a civilian in government service on highly confidential projects.

The intriguing part of this book is the character of this prisoner of war, who was analyzed by a professional psychiatrist as being "… a one-track, furiously working brain, mounted on a neglected over-grown child’s body. […] It is a case of morbid genius very close to insanity by ordinary standards." This report did not prevent the military intelligence services (Navy, Army and Air Force) to provide Cleff with a job in the Ministry of Supply and the Admiralty where he worked, mainly independently, on projects of future developments like supersonic aircraft, ram jets and submarine technology.

All this led the way to a British citizenship as Mr. Peter Herbert. Cleff remained in Great Britain and was mainly employed in technical companies for whom he obtained many patents both in his name and that of his employers. He was an assiduous worker, sometimes dangerously close to a burn-out. He married and died in an accident at the age of 80 in Newcastle.

After the war his claims were compared with what could be established in the conquered industrial areas. The book is not very explicit about these findings. Not even after some of his claims were identified to have mixed up figures about speed; for example miles per hour and kilometers per hour. The impression is made that Cleff had hear-say about many of the developments he claimed would become the victorious weaponry of the Nazis. But that he had not witnessed many of them in real life. And that much of what he drew up for highly sophisticated audiences like the "Supersonics Committee" and of the War Cabinet, had been the product of his technically highly developed, maybe brilliant, imagination.