A Civil War–era historical novel featuring the first female agents in the Pinkerton National Police Agency, who work to foil an assassination attempt on President Lincoln's life.

The year is 1861, the eve of Abraham Lincoln's inauguration. For Kate Warn, the first female private detective in American history, the only assignment tougher than exposing a conspiracy to assassinate the new president is training her new mentee, Hattie MacLaughlin, in the art of detection. The two women's mission to save the president takes them from the granges of rural Maryland to the heart of secessionist high society, and sets them on a collision course that could alter the course of history. When Kate's cover is blown, Hattie must choose between saving her new friend, and her country. Based on a true story.