According to ancient lore, if a human freely offers their heart to a demon, that monster can become mortal, experiencing the true pains and passions of existence. Xiaowei, a millennia-old fox spirit, searches for her chance to become human. Princess Jing flees her kingdom by pursuing the only man she ever loved. A twist of fate brings Xiaowei and Jing together, and a slow game of wits, deceit, and seduction begins for the princess' very own heart.