Lulu's parents refuse to give in when she demands a brontosaurus for her birthday and so she sets out to find her own, but while the brontosaurus she finally meets approves of pets, he does not intend to be Lulu's.

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.