British air defense was unable to intercept the jet, so Captain Francis Blake, squadron leader aboard the aircraft carrier The Intrepid, was sent to meet with the flying wing in a prototype airplane called the Golden Rocket.

Impressed by the capabilities of the young pilot, Major Benson decided with the agreement of Admiral Gray, Chief of Staff, to give him a secret mission to prepare for World War III.

Indeed, services have accidentally discovered that in the greatest secrecy, a secretive dictatorship called the Yellow Empire, ruled by Basam Damdu, has set up an impressive military arsenal and is preparing to attack the West as soon as World War II is over.

Blake receives a pleasant surprise when the engineer with whom he must work is none other than Professor Philip Mortimer whom he met twenty years ago in India.

In the evening, the two friends are introduced to two agents there: Zhang Hasso, a defector from the Yellow Empire and Colonel Olrik, a specialist in Slavic languages.

Mortimer realizes that he and his brother Harvey communicate via the packages they send through an encryption system dating back to ancient Greece, a scytale or Plutarch's staff.

In September 1946, British intelligence services learn that the attack of the Yellow Empire is imminent due to indications of Hasso, who became an undercover agent in Lhasa, but politicians do not want to hear about it.

Blake joins the basic Scafell unaware that a transmitter placed there two years ago by Lieutenant Clarke indicates its location to the Yellow Empire.