It’s Halloween under the sea in the town of Bubbletucky. Join Molly, Gil and the rest of the gang as they go trick-or-treating. Will Mr Grumpfish smile and join in the fun, or is he just too grumpy for Halloween?
The episode starts when Molly greets herself. Suddenly, a doorbell rings and Gil dresses up as a ghost and says "Trick or treat!" and Molly gives treats. Then a doorbell rings again and Gil dresses up a robot and says "Trick or treat!" and Molly gives treats again. Gil dresses up as a wolf and a doorbell rings again. Gil says "Trick or treat!" and Molly dresses up as a witch and says "Boo!" and Gil scares away, and the treats fall on him, and say "It's time for Bubble Guppies!"
The episode starts when Molly and Gil go to a Halloween store. Starfish welcomes us to the store.