Very bad ghost

Otto was sure - the ghosts not to scare him! Still, because he has three ghosts in his house, and the boy gets along well with them. But everything changed when Dragomir Ferrey appeared on Redisina Street. He turned out to be not an ordinary ghost, but by a poltergeist - a violent spirit, who love to cause trouble to living people. Even a skeleton named Harold, a friend of Otto, can not cope with such a dangerous ghost ... Only the overlords of the poltergeist can help here - special agents from the other world. But will Otto and his girlfriend Emily find these mysterious creatures? And convince them to come to Rediskin Street?
In front of you is an unusual, terrible (and terribly exciting) story about friendship and adventure. Girls and boys 10-12 years old who loves secrets and riddles will appeal to her. The book is included in the top 10 of the German Amazon among stories about ghosts for children. Inside, the font is convenient for reading and funny black and white illustrations.
This is the third book of the series, but you can start reading with it.
For secondary school age