"Perhaps the best of the many books on Robert Hanssen (b. 1944), the agent who, for more than 20 years, sold American secrets to Russia. The daughter of an FBI agent, Wiehl, a former federal prosecutor and legal analyst for a variety of networks, delivers a fine account that will make readers squirm but not put it down. The author does not take the easy route by assuming that the FBI was staffed by dimwits, and her unnerving final chapter concludes that, despite some reforms, other Hanssens are not only possible; they’re probably already at work. A superb account of a long-running intelligence disaster."