Dexter appears towards the end of the episode in which he and his parents, Uncle Torbit and Aunt Ophelia, arrive at Owl's house for the family reunion after receiving the invitations from Pooh via balloon. After Rabbit arrives, Dexter watches in horror as Rabbit grabs Dexter’s mother’s tail feather and his mother throws Rabbit across the floor and then Dexter and the family begin telling Pooh, Rabbit, and Piglet about their family history such as their Uncle Tucker spent the summer in that cuckoo's nest.
In the episode, Kanga and Owl drop off Roo and Dexter at Pooh's house so Pooh can babysit them while they go away. Then Roo asks Dexter why they call it babysitting because they're not babies, to which Dexter says, "It is most patronizing. It reminds me of the time..." to which Owl pats Dexter on the head saying: "Oh, yes. The care of children is life’s most important task. Isn't that right, young Dexter?" Then Dexter says, "Oh, indubitably, Cousin Owl." Dexter and Roo then go into Pooh's house, promising Kanga and Owl to be good for Pooh. But they accidentally knock over a pot of honey while playing pillow fight. They apologize to Pooh with Dexter saying, "We'll be delighted to assist in any incompetence that you may require." Pooh doesn't know what that means, but asks them to just help him clean up and then they will pay a visit to Christopher Robin because he has a bigger house to untidy and that they’ll be happy to see one another there. At Christopher Robin’s house, Christopher is about to show Pooh, Tigger, Piglet, Roo and Dexter his science project which is in a box, but his mom calls him to come downstairs and finish his homework. While he's gone, the gang decides to peek into the box and see what the science project is. They open the box and find grass in it, to which they think that the project is outside and not inside, but then they notice a bug in it. They accidentally knock the box over, causing the bug to fall out, and they scare it away.
However, when Christopher Robin returns, he is horrified to find out that Dexter and the others scared away his bug because it was part of his science project, and he needed that bug. Then Dexter and the gang go on a quest to find Christopher another bug. Their journey leads them to Rabbit's garden, where Rabbit was attempting to kill some troublesome bugs. Dexter and friends stop Rabbit and then explain that they need a bug for Christopher Robin to use in his science project. Rabbit complies and tells the gang to help themselves to whatever bug because he has hundreds swarming around. Then the gang comes across a large bug that is shown to be very hungry. Dexter and company befriend the bug and give it some food before convincing it to come with them. They head back to Christopher Robin's house, and Christopher is relieved to have another bug that he can use for his science project at school. When Dexter asks Christopher Robin if this bug will be a science project forever, Christopher tells him not to worry because as soon as he is finished showing his science project at school, he will set the bug free. After presenting his science project at school, Christopher Robin lets the bug go. The bug makes up with some other bugs that were initially not on good terms with it, and they all become friends. The episode ends with Dexter telling Pooh that he makes an excellent babysitter, with Pooh replying in agreement.