"Danny and Lin have gotten pretty good at taking are of tiny dinosaurs so when Lin's mom asks them to babysit Lin's little sister, ChuChu, they're sure they've got it covered. After all, what better place to spend an after noon than hanging out in the Fruity Stars Lab and playing with the Microsaurs? They will be the best babysitters ever! But when the biggest Microsaur they've ever seen starts a stego stampede. Danny and Lin realize they are up for their most important adventure yet. Not only do they need to stop the Microsaurs from destroying the Microterium, but they've also got to save ChuChu!" -- P.4 Cover.