Raised far from civilization, Rayne has spent years mastering the ancient art of beast taming in the mountains, living quietly with his only companion, a scruffy stray dog named Max. When he finally returns to the world below, he seeks out Elena, the girl he promised to marry fourteen years ago.
But the reunion is nothing like the one he imagined. Elena has grown into a noblewoman and is now engaged to a powerful aristocrat, leaving Rayne to bury the feelings he has carried since childhood. Before he can walk away, however, a barbarian army descends upon the city, threatening Elena and everyone she loves.

Forced into action, Rayne begins revealing abilities that should be impossible for an ordinary beast tamer. At the same time, Max's true nature slowly emerges, revealing that the seemingly worthless stray has been hiding a terrifying power of his own.

As war approaches, Rayne must uncover the secrets surrounding his mysterious origins, awaken Max's full potential, and decide whether to reclaim the promise he made to Elena—or sacrifice his own happiness to keep her safe.