London barrister Jason Jonquil has spent his entire life working to establish his identity as a gentleman, a man of refinement like his father and brothers. But when fiery Spanish beauty Mariposa Thornton walks into his office, he finds himself losing his grasp on his dignified character. The woman is infuriating, pushing him to the limit of his legendary patience. However, her case seems simple enough—a small matter of inheritance. Or so he believes.

Once a well-born lady, Mariposa fought to survive the brutalities of Napoleon's war on Spain. She braved horrific perils and undertook dangerous missions on behalf of those fighting against the invading French army. But her greatest battle still lies ahead: after being separated from her family, Mariposa sets in motion a plan to reunite with her loved ones in England. To avoid drawing the attention of the French, Mariposa dons a carefully crafted persona to conceal her true purpose.

As Jason and Mariposa are drawn together by the case, they come to know the people beneath the masks they both wear. When the truth of Mariposa's quest is revealed, the couple is pulled into a mystery that will test the limits of their courage—and expose the true desire of their hearts.