Wilhelmina Cutler had wanted to be a Pinkerton agent ever since she moved in with her aunt and uncle, who was an agent himself. Now's her chance. They are hiring women at the Denver Pinkerton Detective Agency. Already trained in most of the skills needed, Mina is confident she can handle any case they assign her.

Reece Galway is a veteran agent who has worked from the Denver office since the end of the Civil War. When his boss tells him his future employment hinges on marrying a woman aspiring to be an agent, he nearly quits. He's never had a partner and doesn't want one, especially some rookie woman who knows nothing about how to be a detective.

And there's something about his new wife. She seems to attract danger yet is able to stave it off. She's stiff, overly polite, and sometimes rather sarcastic. And she doesn't like his attitude.

Heading to San Francisco to solve an insurance fraud case, Reece and Mina butt heads. Can they work together to solve the case, or will their enmity make it impossible? Will this marriage continue once they are back in Denver or will either one demand an annulment?