A playboy business tycoon, Liu Xuan, purchases the Green Gulf, a wildlife reserve, for a sea reclamation project, and uses sonar technology to get rid of the sea life in the area. Unknown to him, the Green Gulf is the home of merpeople, and the sonar has caused many of them to succumb to illness or die. Xuan's business ventures in the area are threatened when he crosses paths with the mermaid, Shan, who is sent to avenge her people.

Six guitar playing, rock and roll singing and dancing young people on a boating trip are stranded on a rural island off of Hong Kong during a typhoon. They become suspicious of a woman who matches the radio bulletin description of a murderess who killed twelve men. Can she be trusted? Is she laying a trap for a local youth housesitting a mansion?

The adventures of a kind-hearted mermaid who saves a captain's daughter from the stormy ocean, despite the Sea-God's warning not to intervene in the affairs of mortals. However when the captain needs her help again, the mermaid princess must choose between following the laws of the ocean and saving her new human friends from a band of pirates and a dangerous island giant.