York, author of the ""Eliminator"" series and (more recently) two Munroe Tallant mysteries, starts out with a smashing premise in this jaunty mystery/adventure: the exiled Shah of Iran is dying in 1979 Cairo; only he knows the combination to an impenetrable safe back in Tehran, a safe containing the priceless Crown Jewels; in his final delirium, he confides the secret to Egyptian nurse Xeneide. And who, as it happens, has just fallen in mutual love with Xeneide? Bitter ex-CIA agent John Kale, that's who--but, though Kale (now selling tennis rackets to Cairo's European set for a living) has reason to loathe the Company, he patriotically does try to hand over the combination to the local CIA bozo. The bozo rebuffs him, however; meanwhile, a ruthless Savak agent (now working for Khomeini) is after the combination, killing Xeneide. And so Kale, framed for the murder, is soon on the run--hampered by other interested villains (a shady entrepreneur, a Russian agent), aided by journalist Diana (who may or may not be a KGB type). . . until the unmasking of Kale's secret enemy and a revenge-showdown with the Savak killer. The action here slides off into routine chase/kidnap stuff once Xeneide is killed (complete with sandstorm ordeal)--but that strong opening, together with York's breezily professional narration, should keep a fair number of action/mystery readers going.