When he's on his way to see his Orca whale friends. Plunge, the seal meets a Mermaid, who has gotten herself lost. The Mermaid's name is Felicity Rainbow. And she has gotten lost by escaping Ripper the Great White Shark. Who, with his bully friends, are terrorizing the home where she lives. Plunge the seal, along with his Orca whale companions, Oswald, Reef, Echo, and Bubbles, endeavour to find where Felicity Rainbow lives? Then rid the area of the bullies, and return her home. The problem Plunge the seal has, is to convince his Orca whale friends, that mermaids exist?