In The Night by Kathryn Smith

An experienced thief, Wynthrope Ryland is no stranger to beautiful women—or to relieving them of their most valued possessions. But this life of crime is not one he chose for himself, and just when he thinks he has put that world behind him, he is forced to return, to protect the career and family of his brother, North.

Moira Tyndale, a stately viscountess, is his target for this final assignment. But he cannot get close to her without feeling some powerful connection between them. At first he pushes the attraction aside, but as she gives him more and more trust and understanding, Wyn realises he cannot ignore their passion. He knows he must protect her secrets and her past, but he cannot protect her from himself. How can he choose between his heart's desire and his brother's safety?