Auzou Book for octave doesn't want to grow up

When Malo goes on a trip to visit his Scottish correspondent Arthur, he doesn't expect to find himself in a haunted castle! A great opportunity for the ghostly guide and the furry Octave who accompanies him. The holidays are off to a good start! However, as soon as they arrive, the ghosts of the old building begin to disappear one by one… When Octave falls victim to this strange phenomenon, Malo and Arthur have no choice but to call Silène for help: who is after the ghosts?