Just recently, thirteen-year-old schoolgirl Marichka did not even suspect that her typical nine-story house was extremely unusual. Not only do the entrances and apartments sometimes change numbers, the square windows turn, becoming diamonds, and the concrete steps ring like the plates of a metallophone. So, unusual creatures also live in the house - there is a dragon, a werewolf cat, an alien, a time traveler, and many others. With such knowledge there is nowhere to retreat, and Marichka finds herself drawn into the fight against the sinister devourer of magical abilities.