Lady Derring Takes a Lover by Julie Anne Long

A mistress. A mountain of debt. A mysterious wreck of a building.
Delilah Swanpool, Countess of Derring, learns the hard way that her husband, “Dear Dull Derring,” is a lot more interesting—and perfidious—dead than alive. It’s a devil of an inheritance, but in the grand ruins of the one building Derring left her, are the seeds of her liberation. And she vows never again to place herself at the mercy of a man.
But battle-hardened Captain Tristan Hardy is nothing if not merciless. When the charismatic naval hero tracks a notorious smuggler to a London boarding house known as the Rogue’s Palace, seducing the beautiful, blue-blooded proprietress to get his man seems like a small sacrifice.
They both believe love is a myth. But a desire beyond reason threatens to destroy the armor around their hearts. Now a shattering decision looms: Will Tristan betray his own code of honor…or choose a love that might be the truest thing he’s ever known?