When the sun flooded the cobbled streets of the Old Town again this summer, Lena, Maks and Bartek were already planning their next adventure. A holiday in the city seemed dull until Bartek stumbled across something unusual. While wandering through the ruins of an old cement factory, he accidentally pushed aside a piece of rusted sheet metal, under which a cast iron manhole was hidden. A crack in the concrete allowed him to see the darkness hiding underground. - See it! - he called out, waving his hand for his friends to come closer. Lena glanced inside with slight uncertainty. Maks, as usual the first to act, was already kneeling by the edge, shining a torch from his phone. - 'Looks like some kind of old tunnel,' he said, trying to reach the steps of the rusty ladder with his foot. That day, the air beneath the city's belly smelled of dust, damp and something else that none of them could name. After a short deliberation, all three decided to go inside, armed with torches, bottles of water and Lena's notebook, who was always fascinated by abandoned places. The ladder creaked menacingly but withstood the weight of more kids until finally their shoes clattered against the concrete floor. The tunnel stretched far ahead of them, the walls covered with faded drawings and old inscriptions. Lena meticulously jotted down everything that caught her eye. At one point they came across a small alcove where a rusty watch showed the wrong time, although it seemed that someone must have recently knocked it over. Maks directed the torchlight deep into the alcove of the corridor. - Hey, look over there! - he whispered, leaning over something that looked like a fragment of a broken mirror. As Lena bent down, her own face was reflected in the broken glass, but behind her she saw something else - someone's shadow, moving in the depths of the tunnel. Suddenly there was a distant sound from the depths, like metal dragging on concrete. Everyone froze, and hearts began to beat faster. Bartek grabbed Lena by the sleeve. - Someone's here... The tunnel opening led deeper, where the torchlight could not reach. The friends looked at each other - hesitation mixed with excitement. What was hiding in the darkness? Should they go further?