Homer attends a retirement party for Don, the second safety inspector who has been covering for him all these years. Homer is worried about having to actually do his job now.
Marge thinks Homer is working too hard and needs to relax, so she buys the family tickets to the circus. Homer, Bart, and Lisa go to a hypnotist while Marge uses the bathroom. Homer gets hypnotized into believing he's ten years old. The police show up to arrest the hypnotist, but he escapes, leaving Homer believing he's ten.
Homer goes to see Dr. Hibbert who gives him beer. Homer surprisingly spits it out. He tells Marge they need to find the hypnotist to reverse it. Homer sleeps in Bart's room, but his snoring is keeping him up. Marge can't sleep without Homer.
Homer goes to school with Bart and plays tag with him. Lisa gets Homer to listen to her play her saxophone. Bart comes to Lisa for help when he finds out the hypnotist is coming to change Homer back and they run away.
They go to Itchy and Scratchy Land so that Homer can enjoy being a kid for a little longer, but they're caught after only two rides. Homer is changed back. Marge is thrilled to have him back, but Bart misses his friend. Homer goes to strangle Bart but hugs him instead.