Some Like It Wild by Teresa Medeiros

It was to be her greatest masquerade . . .

Pamela Darby needs a man—preferably a Highland brute with more brawn than brains. Determined to save her sister from selling her virtue, the resourceful beauty requires a strapping specimen to pose as a duke’s long-lost heir. Pamela plans to collect the generous reward, then send him on his way. Lucky for the brazen beauty, the seductive, silver-eyed highwayman who just held up their carriage could be her man . . .
Connor Kincaid has given up on his dream of restoring his clan’s honor. And now this plucky Englishwoman is asking him to take part in a risky charade that could land them both on the gallows. Never a man to resist a challenge or the allure of a beautiful woman, Connor strikes the devil’s bargain that could seal both their fates. The highwayman and the hellion journey to London as both enemies and allies—a woman who has everything to gain and a man who has nothing to lose . . . but his heart.