Girl in Disguise by Greer Macallister

Girl in Disguise is a fictional tale based on the real life historical figure, Kate Warne, who was the first female Pinkerton detective. Desperate for a way to support herself, Kate answers a classified job ad she knows was meant for a man, but she convinces Allan Pinkerton to hire her, as women can go where men cannot. Naturally, some of the male operatives in the Pinkerton Agency rail against working beside a female, but eventually, most of the men come to view Kate with respect, even if they still think she's having an affair with the boss. 

Most of the book recounts various cases Kate works. Two notable cases involve Abraham Lincoln; one was while he was an attorney in Springfield and then later on his trip to Washington D.C. for his inauguration. Little hints of Kate's traumatic past are sprinkled throughout until the latter quarter of the book, where Kate's history comes back to haunt her.

In reality, very little is known about Kate Warne's life, but Macallister does a fantastic job of putting the reader in the historical locales where this book takes place and tying in factual historical events to Kate's cases. Macallister also excels at imagining the small details in Kate's day to day life and the difficulties she encounters being the first female private detective. Recommended for lovers of historical fiction and/or pioneering women, as well as anyone who appreciates an author who clearly does her research. Also noteworthy is Macallister's debut novel, The Magician's Lie.