"Which means," said the representative from the Foreign Office, summing up, "that when the Sultan, who is over eighty, dies, we shall not only be thrown out of Qathusn lock, stock and barrel, and the British-American capital which has been sunk in developing oil fields, lost, but also we shall have a rabid enemy at the very gates of Aden, who may very well succeed in alienating the whole of the Trucial Coast and all the other oil States in the Gulf."

There seems to be one faint hope. The late Crown Prince Achmed, murdered at an Embassy reception, is thought to have been secretly married. There may be a grandson of the Sultan living. If so, M.I.5 must find him.

So begins Tommy Hambledon's craziest adventure ever, which takes him in a mad race against time and enemy agents, to Paris, across France and into North Africa, to find a Prince and to avert a revolution.