by Idries Shah.Stein and Day. $17.95. Because Mr. Shah, although living in exile, is still an Afghan, his novel of his countrymen’s resistance to the current Russian invasion has great power of conviction. One is forced to believe that details of guerrilla ingenuity and courage, or of Russian brutality, have come to the author from informants on the spot. The actual plot—pursuit of an antique treasure-may be fiction, but the blood is painfully real.