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.

Olivia, who is very neat and practically perfect, despairs because her sister Sophie is super-completely and totally the messiest person.

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 is sent to Camp Sisterhood to learn how to be a big sister, but she makes it her mission to be the worst sister-in-training in camp history"--

Charlie likes to be ready for anything, imagining that his house could be flooded or a mermaid might kidnap him, but he learns that it is sometimes good to be unprepared.

Friendship overcomes all problems for Rosie and Michael.