A trio of human singers (Francine, Danny, and Roy) are brought to the habitable asteroid by the Coasterville by the "space coaster", a roller coaster-like spaceship. The asteroid is populated by strange-looking, wise-cracking puppet characters, such as Goriddle Gorilla, Knock Knock the Woodpecker, Edison the Elephant. The regular pilot of the space coaster is Baxter the Clown. He is on the run from his former employer, the villainous circus ringmaster M.T. Promises. The ringmaster keeps trying to recapture him and force him to work at the circus.