Zippel is a little castle ghost. But who actually claimed that castle ghosts live in castles? No, Zippel lives with Paul and his parents inside the door lock of their old apartment. Paul discovered him there, and that’s when the funniest time of his life begins. Because Zippel is still a very young castle ghost and always has mischief on his mind. But then the door lock is supposed to be replaced and Zippel’s home is suddenly in danger. Danger is also lurking at Paul’s school in the form of two nasty boys.