The Demon Under the Sofa

Who didn't dream of magical adventures in childhood? Who didn't want something amazing to happen to them? Denis and Polina dreamed too. They wanted it as well. Especially on boring summer days, when they had already tried everything they had planned for the holidays and didn't know how to occupy themselves.
But it turned out that something amazing happened to them. Moreover, it all started quite mundanely - they simply climbed into an old house in search of entertainment. And there... there they found something. An old book in an incomprehensible language. Of course, at that moment they didn't even suspect that this was a very-very special book...