The ancient Miao village "Luoyin Village" deep in western Hunan hides the "Secret of Butterfly Gu" that has been guarded for thousands of years - only the saint of the tribe can activate the butterfly with her blood to resist the strange "fog miasma" in the mountains and forests. However, this secret makes the saint bear the curse of "restraining love". Shen Yan, a local folklore researcher, entered Luoyin Village in order to trace the Miao notes left by his grandfather. He accidentally disrupted the "heart-sealing ceremony" of the saint Ah Jin, and the two were forced to be bound due to a sudden miasma crisis. When Shen Yan tried to uncover the mystery of "butterfly poison and fog miasma" in his notes, he discovered that Ah Jin's fate had long been entangled with secrets: she was both the hope of protecting the villagers and a prisoner imprisoned by a curse.
