To Enchant a Wicked Duke by Christi Caldwell

A Devil in Disguise
Years ago, when Nick Tallings, the recent Duke of Huntly, watched his family destroyed at the hands of a merciless nobleman, he vowed revenge. But his efforts had been futile, as his enemy, Lord Rutland is without weakness.

Until now...
With his rival finally happily married, Nick is able to set his ruthless scheme into motion. His plot hinges upon Lord Rutland's innocent, empty-headed sister-in-law, Justina Barrett. Nick will ruin her, marry her, and then leave her brokenhearted.

A Lady Dreaming of Love
From the moment Justina Barrett makes her Come Out, she is labeled a Diamond. Even with her ruthless father determined to sell her off to the highest bidder, Justina never gives up on her hope for a good, honorable gentleman who values her wit more than her looks.
A Not-So-Chance Meeting
Nick's ploy to ensnare Justina falls neatly into place in the streets of London. With each carefully orchestrated encounter, he slips further and further inside the lady's heart, never anticipating that Justina, with her quick wit and strength, will break down his own defenses. As Nick's plans begins to unravel, he's left to determine which is more important—Justina's love or his vow for vengeance. But can Justina ever forgive the duke who deceived her?