When Lulu's parents go on vacation, the formidable Ms. Sonia Sofia Solinsky comes to babysit and Lulu behaves as badly as possible to get her to leave until Ms. Solinsky reveals her secret.
Lulu needs help from a boy named Fleischman if she is to earn money walking her neighbors' dogs, and she finds out that if she wants her business venture to succeed, she has to be nice.