A yeoman reporting job by Kessler (Moscow Station, The World's Richest Man, etc.), who amasses a wealth of largely circumstantial evidence that naval enlistee Glenn Souther provided the USSR top military secrets. The product of a broken home, Souther grew up in small-town Indiana and Maine. Upon graduating from high school, he joined the Navy, which trained him as a photographer's mate. During his six-year hitch, Souther served aboard the Nimitz and married an Italian woman. Honorably discharged in 1982, Souther enrolled at Old Dominion Univ. in Norfolk, where he majored in Russian. He also signed on with a reserve unit that cleared him for part-time duty at an ultrasensitive installation--the Fleet Intelligence Center for Europe and the Atlantic. His posting to this facility (which not only devises and distributes plans for H-bomb wars but also processes surveillance photos from spy satellites) proved a disaster; somewhere along the line, Souther had begun selling highly classified information to the Soviet Union. Despite tips from his estranged wife and disaffected paramours, the feds did not really get on Souther's case until he bolted to Moscow in 1986. There's no telling how much damage he did to national security. The odds are, though, that it was extensive. As Kessler points out, when Souther committed suicide in mid-1989, he was buried with full military honors as a KGB major. While the author has tracked down and interviewed almost everyone who was meaningfully involved with Souther, he does not have the full story, in large measure because the FBI and other agencies that bungled their investigations refuse to talk. Nor did Kessler (who exchanged letters with Souther) ever meet his subject face to face. Bridging these gaps with informed speculation (disclosed as such), Kessler nonetheless offers a generally gripping account of a personable but troubled and cunning young man's seemingly infinite capacity for betrayal. A compelling and cautionary narrative with appeal that could reach beyond its natural constituency of espionage buffs.