Ola, Igor and Patrycja had no idea that an ordinary Friday evening would change their lives. They met, as usual, on old, abandoned plots of land outside the city, where no one had farmed for years. Their favourite spot was an apple tree, so old that its trunks were overgrown with silvery moss and its roots stuck out of the ground like tangled snakes. - 'I have an idea,' whispered Patricia, with a flash of challenge in her eyes. - Who dares to go under the apple tree and see if the legends of the lost children are true? - 'I'm not afraid,' replied Igor, although Ola knew him well enough to know that he wasn't so confident at all. They slid under the low branches, hiding their torches under their jackets so that the light would not attract anyone from the area. Under the apple tree, the ground was soft and damp. At one point, where the roots formed something like a gate, it was visibly softening. Ola, unable to resist, pressed her fingers into the ground and felt something under her fingers - something hard. - Wait," she said, and started rummaging. After a moment, she pulled out a small iron ring attached to a buried, round lid. - I think it's a manhole - whispered Igor. They were sweating from nervousness and the night air seemed strangely heavy. Patricia pushed the leaves off the lid and together they tried to lift it. It gave way surprisingly easily under their hands. A cool, greenish light gushed from within, illuminating their faces with shadows. In the depths they could see steps leading downwards, where the light of their torches did not reach. - Who goes first? - Ola asked, feeling Igor's accelerated breath on her back. Patrycja was already going down first, without waiting for an answer. There was a smell in the air of wet stone and something else - something unknown that attracted and repelled at the same time. They descended slowly, one by one, until the steps ended abruptly. In front of them stretched a tunnel covered in glistening veins, with blue crystals twinkling on either side of it. From around the bend came a faint pulsing sound, as if the heart of something huge was beating underground. Igor held out his hand to reassure Patricia, but she was already walking on, clutching the torch. Ola felt the ground tremble beneath her shoes. The tunnel was turning, and around the bend they could see a light - much brighter than anything they had seen so far. They stopped just before it, listening. Something moved on the other side, a shadow flitting in the glow. All three looked after each other. It would only take one step to step through the portal and discover where it led....