Nelly is as busy as ever monster-sitting strange and unusual monster babies. With inviting Huffaluks to her birthday barbeque, struggling to frighten Muggots to sleep and stopping Thermitts from melting, Nelly's monster-sitting adventures continue to be full of surprises! It's Nelly's twelfth birthday, and she's invited the huffaluks round for a party. But Nelly's sisters Asti is not happy, and is determined to cause trouble.