Doc comes in with the mail and throws away Traveling Matt's postcard as usual. Gobo enters and gets the card, stating that it was "easy for a change". Doc notices that Sprocket is depressed and concludes the dog is unhappy with his life. Doc suggests Sprocket change his life and even offers to help. Sprocket gets excited and shows Doc that he wants to be a horse. Doc is incredulous at this, but agrees to help.
Red comments to Gobo that it must be easy for him to get his postcards. Gobo shoots back that Red knows no more about Outer Space than she does about Doozers. Red states that Outer Space reminds her of Doozers as she believes both to be really boring. A group of nearby Doozers are heading home after a day's work. They enter the Doozer Dome, a spectacular place where the Doozers live and form their community. In the center of the community is a small park. Some Doozers are talking about doing afterwork chores and activities. Wingnut Doozer drives up and says she's looking for her daughter, Cotterpin, who is scheduled to receive her work helmet in two days. Nearby, Cotterpin and her friend, Wrench Doozer, are discussing getting their helmets so they can become official workers. Cotterpin expresses disgust at the idea. Wrench walks away as Wingnut arrives. Cotterpin feigns sickness due to "overstudying". Flange Doozer shows up and greets his wife and daughter. They find her drawing pictures instead of studying and tell Cotterpin an old tale that if she doesn't study she would grow a tail and become a Fraggle. Cotterpin kinda likes that idea. Flange and Wingnut are shocked at her attitude and send her to the Architect Doozer for "a talking to". Cotterpin goes off to find him.
The Architect is working at his drawing board when Cotterpin pulls up in her little buggy. He is flabbergasted that her parents have sent her to talk to him again. She tells him that she wants "other things" in life. He blows off her concerns and sends her to go study for her helmet ceremony. Cotterpin drives off and sings about wanting to do her own thing in life. She overhears Red and Gobo talking nearby and spies on them. They are talking and having fun and run off to the cave of the Rumble Bugs. Cotterpin is intrigued at the Fraggles. The Architect shouts out for her to come back, but she is torn between going back and following Red and Gobo. She drives off again, totally insistant on being a Fraggle.
Doc buys Sprocket a saddle and has taped horseshoes to the dog's feet. He puts the saddle on Sprocket and the dog runs around the workshop, neighing and galloping like a horse. Doc cracks a few jokes at Sprocket's expense.
Wembley is playing with his toes in his and Gobo's room as Gobo and Red enter. Cotterpin has made her way here as well and peeks through the window, spying on them. She overhears Red talk about the Rumble Bugs and how she learned the Rumble Bug hum and is intrigued. Gobo reads his latest postcard about Traveling Matt discovering a video arcade and how unhappy the Silly Creatures seem to get when they lose at the games. After the reading, Red makes another comment about the Doozers aren't any fun. Cotterpin silently agrees. Gobo mentions lunch and they get excited. Red says that afterward they could make up words to go along with the Rumble hum she memorized. They all get excited, and so does Cotterpin, who wants to join them. But Architect finds her and scolds her for her foolishness. He sends her home to continue studying.
Cotterpin is outside the front of her house studying that night. She is still thinking about hearing Red talk about the Rumble Bugs when Flange and Wingnut check on her. Flange reminds her of the old Doozer tale about one who turned into a Fraggle. Cotterpin thinks that that is what she wants.
The day of the helmet receiving ceremony finally arrives. Wingnut and Flange are excited for Cotterpin, but their daughter is none too thrilled at all. In the park, Architect conducts the ceremony. Wrench, Cotterpin and a third Doozer are standing up, waiting to receive their helmets. Their families and friends are seated nearby. Architect starts singing, asking the three helmet recipients to take their Doozer vows. The whole ceremony turns into a joyful singing fest. Cotterpin shocks the crowd by publicly refusing her helmet. She's going off to be a Fraggle.
Cotterpin arrives at Gobo and Wembley's room and finds a napping Red. Cotterpin claims Red as her favorite Fraggle and goes in to introduce herself. However, she ends up tumbling down the large steps upon entering the room. Blowing that off, she still is determined to talk to Red. She tries waking Red up, but fails at first. After hearing Cotterpin refer to her as the most terrific Fraggle in the world, Red wakes up. She asks Cotterpin why she is here, and Cotterpin says she wants to do the things that Fraggles do because Doozers are boring. Despite the fact Cotterpin is a Doozer, Red agrees to help her out. Cotterpin is off to a bad start as a Fraggle. Her tiny is no match for Red's athleticism. But Cotterpin claims that she can't go back because she'd have to admit she was wrong and she doesn't want to do that. Red tries to keep helping her out.
Red and Cotterpin arrive at the cave of the Rumble Bugs and Cotterpin asks Red to sing her the Rumble Bug hum she memorized. Red obliges. Cotterpin enjoys this greatly. Afterward, Red suggests they go for a swim. This horrifies Cotterpin as she explains that Doozers can't swim, it's impossible. She suddenly realizes that she can never be a Fraggle. She admits she will have to go back and take the helmet after all even though she doesn't want to. Red tries to give her some encouragement and Cotterpin goes home.
Cotterpin drives up to the Architect, who is sitting in the park. She admits that she was wrong to him, but still refuses to take the helmet. He tells her of other Doozers in the past who have refused helmets - himself included. He offers her another alternative: since she loves drawing, she could become an apprentice architect. Cotterpin loves and accepts this idea and the two of them begin talking about drawing different shapes.
Sprocket hangs up his saddle and is exhausted from "being" a horse all day. Doc offers him dinner, which is a bale of hay. Sprocket quickly shoots down the idea of wanting to be a horse and goes back to "being" a dog. Doc admits that he likes Sprocket better as a dog.