Bored with playing school kiddish tricks on one another, the grotesque, satisfyingly revolting couple Mr and Mrs Twit turn their attentions to capturing and training a family of monkeys, the Muggle-Wumps, for a circus act. The monkey's cruel incarceration in a cage is avenged when the birds trick the Twits into believing the world has turned upside-down. The Twits join in, aided by the birds who drop glue on their hair, and the audience is encouraged to play their part in freeing the monkeys.