The siren, who had been sleeping for many years, was awakened and found that the mermaid she had been raised by the fish had been abducted by humans. Now her son is taller than her. What's great is that this child is really obedient, so she might as well abduct her and raise her on her own.
Concept: The ocean is nature's gift to mankind, and the sea monster is the resentment of living beings against mankind.