It was very late when Lena, Michal and Charles met on the old bridge over the Milk River. The bridge, built of cracked bricks, had always aroused their curiosity, especially as none of the adults wanted to talk about it. Under the bridge, the dark water gurgled, its surface reflecting the faint light of lanterns. The city was asleep, but there was a sense of something new in the air. Lena, the bravest of the three, squeezed under the crooked archway and spotted something she hadn't noticed before - a circular door with brass fittings followed by engraved spirals. The door was low, but wide enough for a man to fit through. Michael knelt down beside it and touched the spiral. The metal was warm, as if the door had just been taken out of the oven. "Do you think there's something behind it?" - whispered Charles, usually more cautious. Lena was already pulling the handle. The door opened noiselessly. Behind them stretched a corridor lined with stones that shone slightly under their feet with a turquoise glow. At first they thought it was some old cellar, but the corridor led down deep underground. There were paintings on the walls - depicting animals with long wings, plants they had never seen, and figures dressed in robes of glossy leaves. The deeper they descended, the bluer the light became. Suddenly they heard a distant sound like laughter - or perhaps a cry? They stopped and looked at each other, feeling fear and excitement at the same time. The corridor ended at a tall gate of black glass. Behind it, something moved. Lena reached out to touch it when, at the same moment, a light appeared from the other side - extremely bright and changeable, as if someone was waiting there. At that moment, all three of them held their breath, completely unsure of what they would find on the other side of the gate....