Kilty as Sin by Caroline Lee

He’s a rake, a rogue, and a charmer…until one mission changes it all.

As one of the King’s Hunters—an elite group of Highland lawmen charged with keeping the peace—Barclay is used to lasses throwing themselves at him, despite the helmet he wears on all missions. He doesn’t mind the attention in the least…until he’s assigned to track down the runaway daughter of one of His Majesty’s supporters, and meets a woman who shouldn’t be charmed.
Lady Grace MacDonald is determined not to marry the man her father has chosen for her. She may look fragile and sweet, but she has reserves of strength Barclay is about to discover. Right after he pulls her out of the bog she’s landed in. Nay, not a metaphor; an actual bog has just stolen her left shoe!
Grace might be livid the mysterious, helmed Hunter is planning to return her home, but she still has a few more days to savor her freedom…and Barclay is just the one to teach her about the world. The problem? For the first time ever, Barclay is uncertain he should be seducing a lady like her! But why, even when he’s dragging her back to marry another man, does she make him feel like a hero?