Ala had always known that something was wrong with the tenement house on Wilcza Street. The dilapidated façade, boarded-up windows and twisted bushes indicated that no one had lived there for a long time. However, this is where he and Karol decided to go in when they were bored on the last day of August. They crept in through the basement window, laughing quietly - they were almost adults now, but still loved a bit of risk. Inside it was cold and dark, the air heavy with dust and the smell of old books. Charles lit the way with a torch and Alla followed him, clutching her mobile phone, just in case. They passed through room after room until they came to a room that looked like an old library. There, on the wall where the window should have been, hung a huge, dust-covered mirror in a carved frame. At first it seemed ordinary, but when Alla got closer, she saw that the reflection did not show her, but a completely different place: a forest full of purple leaves and silvery birds. - Karol, look! - Ala whispered, as if the mirror could hear her. Karol stood at her side and froze. Nothing of what was behind them was reflected in the mirror. Instead of the library, they saw a wide forest road, strewn with strange, glittering stones. A figure moved in the distance, followed by a luminous ribbon. Ala reached out her hand and touched the surface of the glass. Her fingers plunged into the mirror like water - there was no resistance, no cold. Charles grabbed her hand and she looked at him uncertainly. - 'I don't think we should...', Charles began, but before he could finish, the mirror flashed and the world behind it rippled, as if inviting them in. Fortunately or unluckily, at the same moment they heard a crash from behind - someone had entered the tenement and was walking straight towards them. Before they had time to think about what to do, something began to happen that they could not explain....