After 9/11, when the nation was still in shock, a mother of three in rural Montana was devouring literature on Islamic culture, teaching herself Arabic, and preparing to infiltrate the central nervous system of global terror: online networks. Shannen Rossmiller's efforts succeeded beyond imagination. Posing as an Islamic militant under dozens of screen aliases, she joined forces with the FBI and started trolling jihadist chat rooms, striking up conversations at 3am with men as far away as Pakistan, and amassing evidence against an array of suspected terrorists both at home and abroad.In 2002,...