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 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).