To Catch A Thief by Anne Stuart

What happens when you take a 1930s comedy like My Man Godfrey and turn it into a Victorian romance? Chaos ensues.
Georgiana Manning has finally found something she wants, something worth fighting for—her family’s mysterious, newly hired butler.

Rafferty is a thief, out to find a cache of money belonging to his former boss. When he’s unexpectedly offered the job of butler in the house where it’s hidden, he jumps at the chance, even though the Manning family’s younger daughter has an inconvenient crush on him.
Rafferty is a lone wolf who plans to stay that way—there’s no room in his life for Georgie. He could find pleasure in romancing her, but he sees no happy ending for a young lady and a thief, or even worse, a butler. Complicating matters, a criminal mastermind is pressuring Rafferty to locate the money, and that mastermind is not above threatening what Rafferty holds dear—Miss Georgiana Manning.
All Georgie wants is the beautiful butler with the piercing blue eyes, though she knows he’s beyond her touch. All Rafferty wants is the hidden money and his freedom. Too bad he’s falling in love.