When the Sea Witch steal the Bubble Guppies' magical jewels so she can rule the Seven Seas, the Guppies must stop her and get their jewels back before it's too late, with the help of their new guppy friend, Zooli.

Dirty Deema the evil ruler wants a medieval kingdom to stay dirty, with Crudly the giant ogre as her assistant and the Knights of Clean under her curse. Molly and Gil must stop them and get the kingdom clean again.