London society knows George Godwin, Lord Eastbrook, as a fun-loving rogue—but since a near-tragedy, George has preferred scientific experiments to scandal. Yet his favorite thing of all is matching wits with Cassandra Benton, a maddeningly clever investigator who works alongside her Bow Street Runner brother. Skilled and shrewd, the Benton twins once helped George's family, and he never forgot the irresistible Cass.

When a long-ago wager resurfaces to endanger the life of George's reckless father, George calls upon the Bentons again to identify the threat. An injury sidelines Cass's brother, so she and George concoct a new plan: Cass will investigate from within the heart of the ton by posing as his notorious (and fictional) cousin. It will mean days and nights at George's side, but the self-reliant Cass is sure she can resist the intoxicatingly attractive heir. If only he wouldn't keep making her laugh, and tempting her into wicked nighttime confessions . . .

As they find passion in each other's arms, love begins to bloom—but danger still surrounds them. Society says they have no hope of a future together. And as the case takes unexpected twists, they might soon have no future at all . . .