Oobi goes to Kako's house for a sleepover. Uma misses Oobi terribly. Grampu does his best to make Uma feel better, but the only thing that works is a phone call and a lullaby from her big brother, Oobi. — ABC Television (source)
Oobi and Uma pretend to talk on the telephone when it starts to ring for real. Grampu picks it up and tells Oobi that someone is calling for him. Oobi takes it and hears Kako on the other end of the line. Kako invites Oobi to his house for a sleepover, and Grampu okays their plans.
While Oobi leaves to pack his things for the night, Uma asks Grampu what a sleepover is. He explains that Oobi is going to sleep at Kako's house. Uma is excited and thinks that she's part of the sleepover, too. Grampu tells her that only the boys will be there, and she gets disappointed. Grampu tries to cheer Uma up by starting a sleepover at their house, but she's still depressed. "Nice try," she tells him as she sulks.
When Oobi is about to leave, Uma puts a photo of her in his suitcase and asks if he will remember her. Oobi assures her that he'll always remember her and closes the suitcase. He explains that he'll be back the next morning, but he's interrupted when Uma hugs him and refuses to let go. He says "goodbye" to her and leaves.
Later, Uma decides to have a tea party by herself. She takes a sip from her teacup and invites the viewers to join her tea party. Grampu walks in and joins as well. Uma asks him to act like Oobi. He plays along and shifts his fingers to look like Oobi's, with some minor difficulty. Uma later asks "Oobi" to play dress-up with her. The next scene shows them wearing hats and purple veils, speaking in posh British accents. They drink their tea, seeming to have a good time, but Uma is then reminded of Oobi's sleepover and becomes very sad.
Grampu leaves her alone as she walks to her room. Uma cries about Oobi until Grampu walks in with the telephone. Oobi is on the other end of the line, talking about how he misses Uma as much as she misses him. He reassures her that he'll be back the next morning. Oobi sings her a lullaby and she slowly falls asleep. Grampu comes in and thanks him for helping Uma. In the next scene, Kako asks the viewers if they have any siblings.
Afterwards, Oobi and Kako are playing with stuffed animals when Mamu tells them to go to sleep. Oobi gets the idea to play a letter game with Kako, using words that start with the letter S. Oobi starts laughing at everything that starts with S, and Mamu again tells them to go to sleep. They turn down the lights and fall asleep as the episode ends.