
Wealthy businessman Damian spends eighty‑million‑dollar funds buying undifferentiated merman Kyle. He dreams of making Kyle differentiate into female to produce self‑healing‑gene offspring, and coerces his wife Nora with special‑effect medicine. Disguised as caretaker “Nell”, Nora approaches Kyle and lures him to differentiate into male on the full moon, ruining her husband’s scheme. In exchange for cooperating in a public showcase, she rescues her mother, reclaims family assets, gets divorced and sets a trap leading to Damian’s death in his counterattack. Though Kyle truly falls in love with Nora, she still has him anaesthetized and exiled to open sea. Kyle braves dangers and swims back to land. After mutual tests, they work together to save captured juvenile mermen, obtain permits to build an ocean rescue center, and gain their destined love.