Nobody in town believed in the Green Tower. Even the history teacher laughed when Tymek, an eleven-year-old with a storm of red hair, mentioned it. But he knew his own - he had heard stories from his grandmother that there was a tower in the middle of the Old Forest that could only be seen during a full moon. On this particular night, Tymek persuaded his best friend Iga to go there together. They were both curious and a little apprehensive. They moved carefully through the bushes, their hearts beating faster with each step. Their torches cast restless shadows on the mossy trees. Suddenly, the moon peeked out from behind the clouds, and a strange glow shimmered between the trees. Iga whispered: - Can you see it? I think it's ... her! The tower was as green as spring grass and seemed to be made of leaves and branches. It had a crooked roof and narrow windows. The door swung open on its own, revealing a spiral staircase leading upwards. On one of the steps lay an old, shiny key. As they stepped inside, they felt warmth and a strange lightness, as if the floor beneath them was breathing. In the air was the scent of forest herbs and.... a hint of magic. Suddenly the door behind them slammed shut with a bang and the key was gone! A soft, melodious voice rang out above their heads: - Those who find the Green Tower must solve its riddle before it disappears with the sunrise.... The children looked at each other with wide-open eyes. A doorway leading nowhere began to emerge from the walls, and a luminous map appeared beneath their feet. They had to choose one of the paths, but each looked equally mysterious....