The Warlord's Promise (Warlords #1)

Kate is a young widow, left alone, having no children of her own, and would do anything to see that her youngest sister, Alison, gets a chance at a happy life. When Alison is taken hostage by an evil warlord who intends to wed her, Kate offers to trade herself to the warlord in place of her sister.

Ethan MacGregor has spent his life fighting among the clans of the Scottish Highlands, trying desperately to bring peace to his territory. Finally ready to settle down and establish a household, he only needs a beautiful young highland lass to share his bed. When he takes the youngest sister of the woman he truly desires, Kate, she falls right into his hands by offering herself in exchange for her sister's freedom.

And though Ethan has promised to release Kate's sister in exchange for a night of passion, he has no intention of letting Kate go.