Good Duke Gone Far by Eliana Piers

To him, she’s a fine specimen of a hellion. To her, he’s the most boring man on the planet. Until they’re stuck in a carriage together and sparks fly.

Lady Kat is on a mission to investigate a mysterious proposal sent from Scotland. Knowing that if she wants something done right, she has to do it herself, she’s up to the task. Nothing can stop her. Society, fate, and even her brother’s best friend can’t tell her what to do. Up until now, this hasn’t gotten her into too much trouble.
But only a few short hours into the trip, Colonel Quinn Hastford tries to stop Kat and take her home. He quickly realizes how futile his efforts are. Instead of protecting Kat from scandal, he now has to protect her from himself as his passion flares out of control.

Will fate force these two together? Or will they choose love all on their own?