From the author of The Zolta Configuration (1983), another stylish if slow-paced spy thriller distinguished by its authentic detail. Here, Quammen offers the complex story of a journalist tracking down a Soviet mole burrowed high in the CIA. Quammen erects his tale on great slabs of conversation about past events, beginning with the late-night talk between nature journalist Michael Kessler, formerly on the CIA beat, and a surprise visitor, ex-spook Melvin Pokorny. Pokorny speaks of Viktor Tronko, a KGB Colonel who defected to the CIA in 1964: despite three years of torture, Tronko stuck to a tale implicating the Soviets in the JFK assassination--and denied the penetration of any top Soviet mole into the CIA. Taking a break, Pokorny goes out for beer and is gunned down. Kessler smells a big story and drives to D.C., where he spends three days interviewing Claude Sparrow, a retired CIA honcho (and an exceptionally vivid character). In lengthy talks, Sparrow details the Tronko affair and tells of earlier testimony by a more reliable defector who claimed that the mole did exist, thus casting doubt on Tronko's denial. Although these gab-fests drag a bit, Quammen punches up the spaces between chatter with a few eerie or violent events: a shadowy figure turns up at Kessler's hotel to deep-throat more info on Tronko; Kessler is pushed off his hotel's scaffolding by an unknown assailant; a second attack results in a stab wound. Then an old pal who fills him in on Soviet connections to Lee Harvey Oswald is murdered. New leads take Kessler to Long Island, where he talks at length with another ex-CIAer. Finally, as if himself weary of all this circular talk, Quammen winds up by tossing in some revelatory twists and spiralling the story into a speedy climax in which Kessler, kidnapped and thrown into the same cell that once held Tronko, pieces together the myriad plot strands. Intellectual spy fare that intrigues rather than thrills. Good fare for patient readers only; others will snooze.