The tale has been told many times, the theories get ever more intricate, but Canute himself could not still the waves of interest in British spy Kim Philby and what author Brown (Bodyguard of Lies, 1975) calls with some justice ``the spy case of the century.'' This book's new wrinkle is that it's a dual biography of Kim and his father, the formidable H. St. John Philby, who was not only a great Arabist and traveler (he crossed Arabia's fearful Empty Quarter), but was almost as puzzling a figure as his son. This one- time employee of the Raj was also an atheist, an anti-imperialist, and a socialist; interned for sympathizing with the Nazis during WW II, he became a communist at the end of his life. Clearly an ornery customer, but, though Brown quotes a KGB spokesman in 1991 calling St. John a ``Soviet asset,'' it is hard to conclude that he was a traitor, and he would certainly have denied it hotly. By contrast, Brown goes fully into the dispute that rages as to where the son's ultimate loyalties lay; in terms of the results--agents captured, missions gone wrong, secrets apparently lost, his ultimate 25-year stay in Moscow--it is hard to conclude that Kim was anything other than the servant of Communism that he claimed to be, a spy so successful that he penetrated to the highest reaches of the British Secret Service and, in Brown's view, made mincemeat out of the CIA into the bargain. (See also The Philby Files by Genrikh Borovik, reviewed on p. 1322.) A judicious summary of the evidence and a riveting account of two extraordinary characters, with all the elements, in John le CarrÇ's words, ``of a great novel, and an unfinished one at that.''