The old tenement on Grzybowa Street looked perfectly ordinary - grey walls, creaking stairs, a courtyard with benches and five trees. But Maja and Tymon knew perfectly well that the most unusual things can lurk in such places. It was summer holidays, the rain was drumming on the windowsills, so they decided to seek adventure in their own home. Maja, a girl with curly hair and a perpetually unbuttoned jacket, had lived on the second floor for years. Tymon, her best friend, had only moved here in May and immediately recognised that the tenement must be hiding something amazing. That day they gathered in the stairwell with torches and notebooks. - 'Did you hear about that locked cellar under the stairs? - whispered Tymon. - Apparently no one has a key to it! - replied Maja. - But they say the door sometimes opens by itself. They crouched under the old oak staircase. Indeed, at the end of the staircase was a tiny wooden gate with rust on the hinges. Tymon gently pushed it open with his elbow - it creaked softly and.... the door gave way. Behind the wicket was a cramped recess. It smelled of dust and something strange, like electricity. A large circular object resembling a clock was stuck on the wall, but instead of numbers it had strange symbols: stars, keys, water drops and arcs. - What is this thing? - Maja asked in a whisper and reached her hand towards the nearest symbol. As soon as her fingers touched the star, the circle began to tremble slightly and glow. A bright light flooded the alcove, and the children felt that something slippery like ice had appeared under their feet instead of the cellar floor. They heard a sound like music, and blurred shapes appeared around them - green, purple, shimmering with a fever of colours. Before they had time to say anything, they felt as if an abyss had opened up a hundred metres below their feet. Suddenly the world was no longer familiar. The tenement dissolved into a bright glow, and they found themselves.... somewhere else. Maja looked around uncertainly. Silver-leafed trees swayed overhead, and glowing mushrooms grew underfoot. In the distance there were tall towers and clouds hovering just above the ground. - Tymon... what is this place? - she whispered. The boy did not have time to answer, because suddenly a voice came from the thicket to their left, as if someone was whispering their names....