Théo is a puppet who looks like a little boy. He is lively, resourceful, imaginative, and funny. Every day, Théo returns from school and goes to play in his room while waiting for his parents to come home. Lou, his favorite babysitter, comes to keep him company and enthusiastically enters his fantastical world. She is the best babysitter in the world! Accompanied by Under-the-Bed-Monster and Soft-Moss, they invent and experience all sorts of adventures.