"Like spies Aldrich Ames and Robert Hanssen before her, Ana Montes blindsided her colleagues with brazen acts of treason. For nearly 17 years, Montes succeeded in two high-stress jobs. By day, she was one of the government's top Cuba experts, a buttoned-down GS-14 with shockingly easy access to classified documents. By night, she was on the clock for Fidel Castro, listening to coded messages over shortwave radio, passing US secrets to handlers in...