Young widow Annabel Chalfont, Countess of Fellbridge, has two small sons to raise, a mountain of her late husband's debts to pay off, and a secret: she's a shadow-shaper, able to manipulate shadow as anyone else might clay. She and six other high-born ladies with equally extraordinary abilities defend England against supernatural crime—but the world knows them only as the Lady Patronesses of Almack's, Regency London's most exclusive social venue.

It's June, which means that the fashionable of London are off to Epsom for the annual race meet. A newcomer is favored to win the Oaks Stakes—a mysterious filly who came from nowhere to win the spring races left and right. It will be up to the Lady Patronesses to discover her identity—while Annabel discovers what her true feelings are for Lord Quinceton...