Oliwia, Maciek and Lena have always enjoyed exploring the mysteries of the old town. That day, they planned to visit the ruined library building on Szewska Street, which supposedly hid the entrance to the underworld. Olive turned down the torch on her phone and quietly entered through the ajar door, followed by her friends rolling in, giggling quietly. The semi-darkness inside seemed thicker than usual, and the smell of damp and dust permeated the air. They walked slowly, between bookshelves that had not been touched by anyone for years. Lena noticed the letter "M" carved on the wall and an arrow pointing down the stairs. "Look! Maybe this leads to the catacombs?" she whispered excitedly. The stairs creaked beneath their feet, and with each step the tension grew. At the bottom stretched a damp brick chamber with four doors. Each was covered with a different symbol: a key, a clock, an eye and a dragon. Maciek looked at one of the doors and noticed that fresh red paint was glistening around the dragon symbol. "Someone has been here before us," he muttered. Suddenly, they heard a soft, metallic sound from behind the closed door. Lena took a step forward as the floor shook slightly under their feet. Their phones had lost range. After a brief deliberation, they decided to open the door with the eye symbol. As Maciek touched the handle, a luminous inscription appeared on the wall: "He who looks will know - but does he understand?". They all looked at each other, and Olive felt her heart pounding faster. The air around her began to pulsate, and a sudden swish and cold blast came from behind the door. The door slowly swung open on its own, revealing a dark tunnel leading into the unknown....