Théo is a puppet that looks like a little boy. He is lively, resourceful, imaginative and funny. Every day, Theo comes home from school and goes to play in his room while waiting for his parents to return. Lou, her favorite babysitter, comes to keep her company and enthusiastically enters her fantasy world. She's the best babysitter in the world! Accompanied by Monster-under-the-bed and Foam-soft, they invent and live all kinds of adventures.