The Bubble Guppies are minding their own business at school, eating some delicious tuna sandwiches...when suddenly their world is hit by the apocalypse, and they are all that's left. Ladybug and Cat Noir show up with a special guest. Will Gil and Molly's love hold them together? Will a new romance arise between Deema and Goby? Will Ladybug, Cat Noir, and the surprise guest save the day and restore earth to its fish-filled glory?