Amber Flame by Hannah Howell

All around the border, battle was a way of life as both Englishmen and Scots rode off across the moors to do as their fathers had done and their fathers before them. So when Storm Eldon was kidnapped by her families ancestral enemies, she knew there were rules to be honored by both sides. If her stepmother agreed to the ransom demanded, Storm would not be harmed by Tavis MacLagan, the handsome highland warrior who held her captive. But as days of waiting turned into weeks, it began to be clear that in this contest of wills, no one was fighting fair. Tavis' hands-off policy had changed into an all out siege of the senses, and Storm realized she was less interested in guarding her virtue than becoming...His Bonnie Bride.