Nelly Rapp is a 10-year old girl with no friends. She and her dog begin an autumn holiday with her eccentric uncle. Soon she notices that Uncle Hannibal is a bit different. Snooping around his mansion, Nelly learns an incredible secret. Her family are members of an international brigade of Monster Agents, and soon Nelly gets dragged into an adventure filled with ghosts, vampires and werewolves.
