Selene, a lonely orphan girl from a fishing village, rescues Kaelen, an amnesiac merman‑prince trapped in a fishing net. A drop of his blue mer‑blood leaves a mysterious scale‑shaped mark on her wrist. Hiding him from greedy villagers, Selene shelters the injured youth, who later takes human form under the name Ahai. Though Ahai uses ocean powers to help local fishermen, ruthless townsfolk covet his magical tears and blood that turn into pearls. Cornered and hunted, the merman prince unleashes devastating sea power to stop a tsunami, sacrificing his memories to save the village. Years later, Captain Selene sails across endless oceans, until she finally finds the amnesiac Ahai stranded on a desolate island.