On one level, Lis Wiehl’s enthralling and grimly astonishing A Spy in Plain Sight is simply the story of Robert Hanssen, an FBI agent whose espionage activities were described by the Department of Justice as “possibly the worst intelligence disaster in US history,” a crowded field even at the time of his arrest in February 2001. “Over twenty-two years,” explained the DOJ in a 2002 report, Hanssen had “given the Soviet Union and Russia vast quantities of documents and computer diskettes filled with national security information of incalculable value.” And his betrayals had cost lives. Wiehl cites three (although there will have been more): each had been fingered as American agents by both Hanssen and Aldrich Ames, Hanssen’s predecessor as, in Wiehl’s description, “the most notorious spy in modern US history,” which gave the Soviets the corroboration they appear to have required.