Most London socialites dream of marrying for love or status, but Contessa's wedding is about justice—and revenge.

Nathanial Woodrow is known on the streets of London as the Beast, leader of the fearsome Lion gang who mark their victims with three slashes on their face. Since her mother was found dead with the signature slashes years ago, Contessa has wanted nothing more than to see her murderer brought to justice. However, the Beast has been impeccable at maintaining his façade as the high society Mr. Nathanial Woodrow, and nobody has been able to gather enough evidence to convict him. When the Beast unexpectedly asks Contessa's father, the Chief of the Royal Police, for her hand in marriage, Contessa and her father hatch a plan to bring him down from the inside.

As Contessa enters the lion's den in search of evidence to convict the Beast, she finds that not everything is as she once thought. Her father's work, hunting down Talented that use their magic to rule the criminal underworld, is thrown into question with each glimpse of the kind-hearted man beneath the mask of a hardened gang leader. As Contessa navigates her search for justice, she finds herself questioning what side she's really on, and why she finds herself drawn to a man she's supposed to hate.