Molly, Gil and Bubble Puppy come across a lost kitten. When she follows them to school, the class begins to think about cats.
Before Molly can introduce the show, a ball of yarn rolls past her. Chasing the yarn is Gil, dressed up and acting like a cat. Molly asks the viewers what Gil is pretending to be as he licks his paws and purrs. Bubble Puppy sneaks up behind Gil and barks loudly, making him jump! Gil then announces "It's time for Bubble Guppies!"
Molly, Gil and Bubble Puppy are on their way to school, when Bubble Puppy hears a noise from behind a bush. The three of them find the source of the noise: a lost kitten. Although the cat is friendly, Bubble Puppy does not seem to like her very much. Molly and Gil say goodbye to the kitten as they continue to school. When Molly and Gil arrive, they tell the class about the kitten, which they soon find has followed them all the way to school! Mr. Grouper discovers from her collar that the kitten's name is Bubble Kitty, and all of the guppies admire her. Mr. Grouper gets the kids thinking about cats, inspiring the Bubble Guppies to sing the song: Here Kitty Kitty!
After the song, Gil visits Deema's new store 'Jungle Gym Dandy', as he needs a place for his black leopard to play. Deema suggests that they build a jungle gym for Gil's pet. The jungle gym is made up of 3-D shapes, and Deema asks the viewers to help her choose the correct ones for the structure. Another 'cat-isfied' customer! Mr. Grouper then announces that it's lunchtime.
Molly tells the viewers that big cats like to do different things, like climbing and swimming, when photographer Gil joins her. Gil is looking for a tiger, and spots one in some bushes nearby. The 'tiger', however, turns out to be Bubble Puppy in disguise, giving Gil another fright! Molly then invites the viewers back into the classroom.
Nonny, Gil and Deema are pretending to be big cats, with Gil as a cheetah, Nonny as a lion, and Deema as a leopard! Goby is busy drawing, whilst Oona and Molly try to cheer up a sad looking Bubble Kitty. The Guppies think that Bubble Kitty misses her owner, and suggest to Mr. Grouper that they should help reunite them. Goby's recent drawing of Bubble Kitty makes a perfect poster, and the little fish set out to hang it somewhere in town. It's then time to go outside!
Oona and Goby pretend to be cat herders, whose job is to protect the animals that live in the big cat reserve. They are told that several baby cats have gone missing, and to watch out for the cat burglar. The cat herders travel to Africa, India and Peru, each time saving a cub from the cat burglar. However, as Oona and Gil rescue the last cub, they are cornered by the cat burglar! Luckily, a lion comes to their rescue, the daddy of one of the cubs they saved, and scares the cat burglar up a tree. He reveals that all he wanted was to pet the little cubs, so Goby and Oona make him a cat herder too, and they all lived happily ever after! Gil then invites everybody to do the The Paws Lickin' Dance!
After the dance, Gil reveals that he is now looking for a lion. Despite Molly's doubts, Gil is sure there's a lion nearby. Once again, the lion turns out to be Bubble Puppy, who pounces and scares Gil again! Oona then tells Molly that their poster worked, and that they can finally reunite Bubble Kitty with her owner. Molly invites the viewers along for the field trip.
Mr. Grouper and the Bubble Guppies arrive at a large mountain, where they spot Bubble Kitty's owner waving at them from the top. However, she leans too far forward and falls over the railing! She manages to save herself by hanging on to the sheet covering the mountain, but it won't hold for long. Everyone races to the top of the mountain. Deema finds an incredibly large ball of yarn, which they use to pull Bubble Kitty's owner back up. Even Bubble Puppy helps out. Everyone then gets to see 'Meow-nt Rushmore': a collection of big cats sculpted into the mountain, including one of Bubble Kitty.
Just before the show closes, Molly and Gil hear the sound of a jaguar. Gil sees a tail at the top of a tree, but assumes that it's another joke from Bubble Puppy. Once he sees that it's not Bubble Puppy, Gil runs for his life! The camera zooms out, however, revealing that Deema and Goby are behind the trick this time. Everyone laughs as the show ends.