Tide in the Palace

For ten years, the emperor's favorite concubine hasn't aged a day. Strange sounds echo from her chambers each night. Guided by a soul pearl, a mermaid enters the palace disguised as a maid, searching for her long-lost sister. As servants vanish and whispers of an immortality ritual spread, she joins forces with the empress to expose the truth at a grand ceremony. But will she find her sister before the palace claims another victim?