On a full moon night, under the deep sea, an ancient song is about to awaken, and a decision concerning the balance of the world quietly comes.
Su Nian, a cold folklore professor, received an invitation to cooperate from the mysterious wealthy businessman Gu Yeshen when his family research institute was on the verge of bankruptcy. The goal is to explore the ghost ship that only appears on full moon nights every sixty years - the "Moon Shadow". The deadly song lingering on the ship is an ancient mystery in her professional field. In order to save the family business, she resolutely stepped into this forbidden sea.
However, what Gu Yeshen is looking for is not gold and silver. He is burdened with the "deep sea curse" passed down from generation to generation in his family. Every time he approaches the singing, his body will undergo irreversible alienation. He needs Su Nian's knowledge as the only key to solving the curse. In the "memory corridor" constructed by singing, the two were forced to face their deepest fears and desires: Su Nian witnessed the sacrifices made by his ancestors to protect the secret; Gu Yeshen relived the century-old pain of his family being tortured by the curse. In mutual redemption, the cold alliance of interests sublimates into a fiery life-and-death dependence.
But the truth is far crueler than they imagined. The ancient song comes from the "Tears of the Siren", a sacred object that maintains the balance between the two worlds, and the curse of the Gu Yeshen family is actually the bitter fruit of the ancestors' betrayal of the contract. When another dark force trying to control the world's oceans, the "Deep Tide," struck, Su Nian and Gu Yechen were forced to stand at a crossroads of fate.
