The Guardian’s Bride by Susan King

She once saved his life and stole his heart. Now he must return the favor.

Accused of poisoning the English king, healer Lady Rowena Keith ends up in a dungeon beside a brawny, snoring Highlander. After he dispatches an assailant, he escapes into the Scottish hills, hauling her with him. To her surprise, she recognizes the rogue as her childhood betrothed and the knight whose life she once saved. Now he is her only hope.
Accused of treason, Sir Aedan MacDuff, a loyal knight and guardian of Scotland, must secure a legendary treasure. He doesn’t need the hindrance of a prim, beautiful healer, even one who captivates him. Traveling in disguise to avoid capture, they soon discover passion together—and find a mysterious link between Rowena’s healing stone and the treasure Aedan is protecting—one that could change the future of Scotland forever.