The mermaid's tears turned into gilded gold, at the cost of permanent skin ulceration. Three years ago, wealthy merchant Karen abducted the young mermaid Xi and imprisoned her to produce gold. Her sister Lan endured for three years and disguised herself as a human to sneak into the rich man's villa. She secretly allied with the oppressed maid Ella and witnessed her sister suffering and almost losing her body several times. After awakening her hatred, Lan spared no effort to cause her body to rot and lead the underground flood, destroyed the breeding farm to rescue Xi and her fellow tribesmen, submerged the luxurious villa area, and returned to the dark river with her tribe covered in scars.
