A CIA analyst--collaterally descended from Nathan Hale--does battle with an Iranamok-style governmental cabal planning to vaporize a good-sized chunk of Tehran. Silas Sibley's vocation is intelligence-gathering. He runs an experimental CIA computer capable of passively bugging countless telephones, as well as their surrounding offices, and electronically analyzing the information. Sibley's avocation is history. He's working on a startling analysis of his very granduncle's decision to spy for his country. Sibley's electronic ear is supposed to be picking up only Soviet chatter, but he's been unable to resist tuning in on his loathsome CIA training classmate, a slimeball named Wanamaker--which is how he overhears Wanamaker's plans to smuggle enough uranium into Iran to result in a very convenient atomic blast. A horrified Sibley thinks his beloved CIA is behind the scheme, but it's actually a renegade operation run by someone awfully close to the President. Sibley's anonymous threats to expose the plot lead Wanamaker to hire Admiral Toothacher, a retired spymaster, to ""walk back the cat""--spy talk meaning to discover the leak and plug it. When the Admiral gets too close, Sibley flees his New York hideaway and heads for New England--where he combines scholarly research with his private war and finds that his situation has become eerily like that of Nathan Hale. Littell (The Revolutionist, 1988, etc.) mixes pieces of the Hale biography with the brainy and amusing present-day spychase, but the distraction is not unpleasant. The eventual fusion is, however, a bit baffling.