Handsome cavalry officer Sir Gabriel Boscastle returns from Waterloo a hero, only to resume his pursuit of forbidden pleasures in London. There is no bet this cynical gentleman will not take—and no woman he cannot seduce. But when he travels to the country manor he wins during a card game, he discovers there is one gamble he has never risked and that he may have met his match. His opponent and neighbor is none other than Alethea Claridge, the only person who stood by him during his wildest years and the only woman ever to captivate his heart.

The beautiful and solitary Lady Alethea is seemingly still mourning for her fiancé, who died in battle. But beneath her shield of feigned sorrow, she hides an unspeakable secret—one that could destroy her reputation forever. So when this dark horseman thunders back into her life one night, she is understandably wary of him. She had defended Gabriel once when he was a wicked boy. But now, as a beguiling man, he makes his sensual desires well known even as he swears he will reform. Will the irresistible scoundrel redeem himself and restore her trust in love or ruin her completely? She will soon have her answer as Gabriel challenges everything she believes about love, about herself, and about what it takes to be a hero.