Love cannot resist an unbreakable heart...After losing the love of his life, Liam of Clan Kincaid is sent in service for what his uncle considers betrayal. He regrets the harsh words he had with his uncle, and so Liam gives himself to the battle-weary king, Robert the Bruce, and vows to mend his tarnished reputation. That would be easy if not for the lass who insists he aids her.Makenna Mackenzie has lived through hell, her home and land taken, by the English. All she wants is to take vengeance against the man who cut off her ear and destroyed everything held dear in her heart. The only way to achieve her goal is to plead with the legendary king's guard. She wants them to train her to be a mercenary like them so she can use her sword to the fullest when she finally meets her enemy.Neither of them ever thought to find one another since their betrothal never came to fruition. But when Makenna asks for his aid, Liam agrees with one condition-that she marry him. Makenna has conditions of her own, and they make a pact to help each other. Their agreement leads them on a dangerous mission, one of which might be the end of them both. Liam finds himself in a quandary because Makenna is not the forthright lass he deems her to be. But his UNBREAKABLE HEART can withstand her, can't it?