The Sea Witch steal the Guppies' magical jewels so she can rule the Seven Seas; the Guppies must stop her and get their jewels back before its too late.
The episode starts at the school, where Mr. Grouper gives the Guppies some exiciting news: they have a new student joining their class. The Guppies were very excited. Mr. Grouper explained that their new classmate is a girl named Zooli, who will be at school later today. Mr. Grouper and the Guppies take a look at a video she sent to say hi.
In the video, Zooli introduces herself. She reveals some things about herself, such as her favorite color (purple) and her favorite ocean animal (a seahorse).
After Zooli's intro the Guppies talk about their favorite ocean animals. Goby says he likes sharks. Mr Grouper gets everyone to think about animals that live in the ocean (sharks, octopi and seahorses) This inspires the Guppies to sing Ocean Animals.
It is then time to go outside. In an underwater kingdom, the Guppies have special jewels that turn them into ocean animals until 1 day when a purple tentacle stole Oona's jewel. She went to tell King Grouper about this immediately! Nonny told the King someone stole his jewel too. Luckily Mr Grouper knew someone who could help; the Princess of the Narwhals Deema.
The 4 kids went to find Deema. Oona and Nonny told her someone stole their jewels. She had 5 ocean animals to choose from. Oona told her the 1st clue was purple. With the viewer's help she answers it had to be 1 of 3 sea animals. There was only 1 more clue it had tentacles. The only ocean animal that was purple and had tentacles was an octopus. He stole their jewels.