At the beginning of the universe, monsters were rampant on earth. The great god Biao Yuntai used the magic flute to seal the monsters, but the three gatekeepers were careless and the monsters escaped. Since then, the monsters and the immortals have attached themselves to human flesh and started an endless confrontation. Time flies. During the Joseon Dynasty, there was a Taoist priest named Tian Yuzhi (played by Kang Dongyuan) who was highly skilled in Taoism and had a romantic nature. He used magic to tease the king for fun, and fell in love with a beautiful young widow (played by Lim Soo-jung). In order to reach the highest realm of Taoism and transform his dog follower Xiaoyi (played by Liu Haizhen) into a human, Tian Yuzhi searches for the magic flute and bronze sword. He unexpectedly clashes with Mr. Huatan (played by Kim Yun-seok) who has the same goal as him. As a result, his mentor is killed by Huatan, and he and Xiaoyi are sealed in the painting by three gatekeeper gods... Five hundred years later, the monster reappears in the world. The three gatekeeper gods don't know where Huatan is, so they have to release Tian Yuzhi to subdue the monster. A generation of Taoist priests finally see the light of day again. Is the fateful love still waiting for him? How to end the grudge with Huatan?