The show features three small supple young children, the Plonsters. They are Plif (the green plonster), who likes to do practical jokes, Plops (the blue plonster) who is the cranky one and Plummy (the orange plonster) who is the cheerful one. They can morph themselves into anything, and their language is some kind of gibberish. The plot of the show is usually that Plif and Plops play all kinds of pranks on Plummy, but she gets back at them every time, and every episode ends with the three of them playing together peacefully.