Connor Grant has a very unique position with a very specific task. As personal assassin for King James (I and VI, for England and Scotland, respectively), Connor makes use of women as spies to help track down his targets. In February of 1605, the reluctant yet diligent assassin seeks a new addition to his group of trusted assistants.
Arianna Fitzroy runs a dangerous game of her own: cheating at cards in order to earn the money to pay the few servants she has left after the death of her brother, who managed to run through the family money and Arianna’s dowry in short order. When Connor spots her and confronts her with knowledge of her activity at a royal party, he also offers her a way out: join his band of spies. Feeling as though she has no choice, Arianna agrees.
Arianna becomes engrossed in the rigorous training necessary for her new position, which includes physical prowess as well as flirtation techniques. While his ladies train, Connor learns his sister, Cora, hidden away at a convent to keep her safe, has been receiving visits from a man Connor fears may be up to no good, so he resolves to complete his current mission and move his sister as soon as possible. Matters become more complicated for both Arianna and Connor when they both realize the bond they have formed may go deeper than may be wise for their situation.