Recently returned to England, Leo, the new Earl of Salcott, discovers he's been thrust into the role of guardian to an heiress, the daughter of a notorious rake. Even worse, his wealthy ward has brought her half-sister, the beautiful but penniless Isobel, with her. Leo must find Clarissa a suitable husband, but her illegitimate half sister, Izzy, is quite another matter. Her lowly birth makes her quite unacceptable in London’s aristocratic circles.

However, the girls are devoted to each other and despite the risk of scandal if Izzy’s parentage is discovered, they refuse to be separated. To Leo’s frustration, nothing will convince them otherwise. Even worse, sparks fly every time Leo and Izzy interact.

Called away to his country estate, Leo instructs the young ladies to stay quietly at home. But when he returns, he's infuriated to discover that Izzy and Clarissa have launched themselves into society — with tremendous success! There's no going back. Now Leo must enter society to protect Clarissa from fortune hunters, and try not to be driven mad by the sharp-witted, rebellious, and intoxicating Izzy.