George Inigo, an expert on the USSR at the CIA, is suddenly called on to be the CIA representative at the SALT II talks in Geneva circa 1978. (First-novelist Whitman had this very same post--largely a matter of evaluating the verifiability of specific arms-control provisions--as the CIA's head Soviet-policy analyst till 1979.) And at first Inigo is only mildly involved in his new position, spending much of his time in broodings on his lonely widowerhood and in courting an attractive German woman (a fellow skiing enthusiast). Then, however, Inigo learns that his predecessor in the CIA spot was murdered. Moreover, this unsettling discovery is quickly followed by a surprising communication from Smirnov, the sly KGB man who is Inigo's opposite-number at the SALT talks: ""I wish to defect to the United States of America."" Inigo is naturally suspicious at first, fearing a trap. But when Smirnov offers to prove his genuineness by leaking crucial SALT data (the USSR's ""fallback positions"" on key provisions), Inigo begins to trust the KGB man--and even believes his version of the previous CIA man's death. (He was a would-be defector to Moscow, killed by the ClAD Still, there are problems ahead for the defection scheme: Smirnov insists that the US bring his young daughter out of Russia (a tricky proposition); the Russians realize that someone on their side has been leaking data, so Smirnov is in danger; Inigo worries about his new affair with Erika--especially when he learns that she's an East German agent. And finally things go more or less as planned, with surprise-help from Erika. . . and a surprise-move by Mrs. Smirnov. Whitman offers a fair amount of insider detail and texture here--some of which is intriguing, much of which will interest only those who are keen, in-depth followers of the SALT negotiations. (A fairly typical piece of dialogue: ""So what's left?. . . Just the new-types rules for ICBMs and the frods for Bison tankers, right?""/""Don't forget telemetry encryption."") Otherwise: a sturdy, fairly standard, rather talky and earnest defection-thriller--with a few nice touches but little originality, especially in contrast to Len Deighton's latest batch of fresh variations on the defection formulas (in Mexico Set, above).