When Maud's perfect twin sister, Milly, plans a sleepover, Mum forces Maud to have her friends over, too... What can possibly go wrong? Nothing much... just that Maud's mum might find out about Rotwood High being a school for real monsters! As if that's not enough, Maud is tricked into looking after Violet, the school hamster, by her archenemy, bitchy-witch Poisonous Penelope. But Violet is no ordinary hamster! She's a pedigree vampster and an expert cage-breaker. With a vampster on the loose, sleep is the very last thing that happens!