Inspired by the real story of investigator Kate Warne, this spirited novel follows the detective's rise during one of the nation's times of crisis, bringing to life a fiercely independent woman whose forgotten triumphs helped sway the fate of the country.

With no money and no husband, Kate Warne finds herself with few choices. The streets of 1856 Chicago offer a desperate widow mostly trouble and ruin—unless that widow has a knack for manipulation and an unusually quick mind. In a bold move that no other woman has tried, Kate convinces the legendary Allan Pinkerton to hire her as a detective.

Battling criminals and coworkers alike, Kate immerses herself in the dangerous life of an operative, winning the right to tackle some of the agency's toughest investigations. But is the woman she's becoming—capable of any and all lies, swapping identities like dresses—the true Kate? Or has the real disguise been the good girl she always thought she was?