On a hike deep in the Rocky Mountains, Kai Monahan watches as a dozen dragons--actual freaking dragons--battle beneath a fat white moon. When one crashes nearly dead at her feet and transforms into a man, Kai does the only thing a decent person could: she grabs the nearest sword and saves his life. As the dragon/man, Rhys, recovers from the attack, a chance brush of skin against skin binds him inextricably to Kai. Becoming heartsworn to a human--especially such a compelling one--is the last thing Rhys wants. But with an ancient enemy gathering to pit dragons against humanity and his strength nearly depleted, Kai has just become the one thing Rhys needs. A complete bond will give him the strength to fight; a denied bond means certain death. Kai is terrified at the thought of allowing any dragon into her mind...or her heart. Accepting the heartswearing and staying with the dragons means sacrificing everything, and Kai must decide if her freedom is worth risking Rhys's life--a life more crucial to the fate of humanity than she could possibly know.