The Duke’s Stolen Heart by Carrie Lomax

Miss Antonia Lowry’s beauty and wit have gained her access to England’s highest social echelons. Each trinket she pockets from London’s haut ton brings her one step closer to freedom—or the hangman’s noose. As suspicion mounts, London’s best jewel thief decides it’s time to bid adieu to her false identity…but she may have overstayed her welcome.
The Duke of Havencrest requires Miss Lowry’s assistance to regain possession of the famous Heart’s Cry necklace. He is not above using blackmail is what it takes to force the thief’s hand. Yet the prickly woman draws him almost as much as her talent for relieving ladies of their valuables. Faced with discovery, Antonia agrees to help him in exchange for enough gold to last a lifetime. One final theft, and she’ll be safe forever.
Yet the closer they get to their shared goal, the harder it will be for Antonia and Havencrest to part ways… Can a thief fit into a Duke’s world, or will more than laws be broken?