It seems that a poltergeist has appeared on Radishkina Street! This is not an ordinary ghost, but an evil spirit who loves to harm people. Dragomir the Fierce (and this is the name of this spirit) is sure that there is a treasure hidden in Otto’s garden - a gem that can make the ghost invulnerable. And the poltergeist is ready to do anything to take possession of this treasure! Even Harry’s skeleton cannot help Otto; he cannot cope with such a strong ghost. The boy has only one thing left: he must find the poltergeist lords, special agents from the other world, as soon as possible. The trouble is that they are very mysterious and very busy creatures. How to convince them to come to the rescue?