When a Highlands' castle is besieged by Scottish armies loyal to the English crown, the call to war is answered by many advocates of Scots' freedom. Austin Merrick, a skilled and respected lieutenant of his father's army rises to the challenge, as does Fiona Rose and her ragtag group of soldiers, what remains of the Roses, the Merricks' longtime enemy in the north.

Austin scoffs at Fiona's presence on the battlefield, deeming it inappropriate for a woman to fight, while proud Fiona challenges his prejudice and proves her worth in combat. However, in the chaos of battle, both Austin and Fiona are captured and find themselves imprisoned together, intensifying the conflict between them at the same time flames of desire are kindled. The pair escapes, embarking on a journey through the harsh Scottish Highlands, forced to rely on each other for survival.

Though possessed of a warrior's spirit, Fiona knows that same strength acts as a shield, protecting her from the vulnerability of emotional entanglements. Matters of the heart are a potential source of weakness, which she, more than most, cannot afford to entertain. Likewise, Austin grapples with conflicting loyalties between his duty to his father and kin and his growing feelings for Fiona, an enemy to the Merricks. Despite Austin and Fiona's mutual reluctance to surrender to longing, neither proves to be stronger than their desire.