In the new, musical animated film from the School of Monsters series our heroes go to far Bu-Yorke to examine his sights, to bypass all fashionable boutiques and, certainly, to celebrate emergence of a rare Crystal comet. But business won't be limited to only one holiday. Catty is waited by tests with which she won't be able to cope without the aid of friends. And to defeat the opponent, friends should solve the mystery of the Crystal comet. And differently Catty is waited by terrible destiny!