Amaryllis Fox

In 2009, Amaryllis Fox flew to Pakistan in the hopes of convincing representatives from three extremist groups not to detonate a bomb in the middle of a crowded city center there. Here’s a community center you would hit, she told them, pointing at a spot on a tourist map. Here are two schools. Here is a mosque. Innocents would die, she told the men, all of whom had ties to Al Qaeda and the Taliban. Americans would die, yes, but so would Muslims, in even greater numbers. Fox appealed to them as men of honor, as men of God. Do not do this thing, she told them.

Before this fateful meeting in a cramped, book-filled apartment in Karachi, Fox had already spent much of the past decade as an undercover officer in the CIA. Over the years she had tracked the flow of weapons of mass destruction ...