Stealing a code book from an enemy spy should be easy for someone like Frederica Vale. As the plain-looking older sister, she's practically invisible at social events. Never mind that she has no experience as a spy or that the codebook rests in the possession of one of the most powerful men in England. Freddie has no choice - she's desperate to save her young sister from the lecherous intentions of their guardian and recovering the book is her only option.Tristan Graylocke has never been able to measure up to his brother, the Duke of Tenwick. But being second best has its advantages. No one pressures him to get married and produce an heir, leaving him to carouse at will - an activity that lends itself perfectly to the brothers' secret lives as spies.When an alluring enemy spy shows up at the house party planned specifically for the purposes of passing along a code book, Tristan finds himself drawn under her spell. Freddie seems innocent and inexperienced. Is her innocence a clever guise, or is she being coerced by someone?Tristan and Freddie soon find themselves engaged in a seductive game of cat and mouse where each will do what they must for their country, especially if it involves kissing the enemy.