Hilla, Kaapo, and Maikki are being watched by a nanny while their parents are out. The only problem: their nanny is a monster! Grah is hairy, dusty, extremely lovable, and doesn’t speak. When the siblings discover that the neighbor's kids are also being looked after by monsters, they start to wonder where all these monsters suddenly came from and why they sometimes seem so unhappy. Together with Maikki's talking bathrobe and a very helpful monster dictionary, they try to uncover the mystery of their new friends. An unusual adventure full of bizarre humor and imagination.