In a Regency London that isn't quite the one we know, young women of families whose reputations have been ruined are known as the Fallen. Young Sarah Tolerance is one such: a daughter of the noble who ran off with her brother's fencing master. Now he's dead-and everyone expects Sarah to earn her living as a whore. But Sarah invents a new role for herself, and a new vocation: "Investigative agent" With her equivocal position in society, Sarah is able to float between social layers, unearth secrets, find things lost, and lose things too dangerous to be kept. Her stock in trade is her wit, her discretion, and her small-sword - for the fencing master she loved had taught her that as well. And she will need all her skills, when she is approached by an agent of the Count Verseillon. The task seems routine: reclaim an antique fan he once gave to "a lady with brown eyes." The fan, he tells her, is an heirloom; the lady, his first love. But as Sarah Tolerance unravels the mystery that surrounds the fan, she discovers that she - and the Count - are not the only ones seeking it, and that nothing about this task will be what it seems.