A US Air Force plane mysteriously vanishes on a flight from its base in Britain. The C.I.A investigation of the missing pilot turns up odd information. A search of Major Davies' cottage reveals a strong interest in the literature about King Arthur. Strangely too, there are important links between Arthurian research and key documents held in Russian libraries. And there are some curious rumors that the KGB is also investigating the precise site of the Arthurian Battle of Badon. What possible concern can the Soviet secret police have in the site of a 6th-century battle? Why should the Russians have shot down Davies - if indeed they did? And why should the C.I.A be so concerned? The top British agent, Dr. David Audley, becomes deeply involved before he realizes that he is being brilliantly conned…