In Regency England, Cascabel Gray dreams of freedom - and disguises herself as a boy to secure a place at Oxford University. After all, she's as comfortable in breeches as she is in ballgowns.

Her plans are upended, however, when she receives a blackmail letter from Charles Lafleur, a member of infamous secret society the Rogues Club, threatening to expose her.

But when Lafleur is found dead, the plot thickens... and Cascabel becomes a prime suspect in his murder. She joins the Rogues Club to conduct an investigation of her own, and her life soon begins to spiral out of control.

To survive, she must switch between her male and female personas, attracting both fellow student William Grenville and a chambermaid known as Mouse - and even attending a ball with an Austrian prince. Can she find a way to balance her double life and clear her name, before she loses everything?