When Gaia first crossed the threshold of the old city library on Vistula Street, she did not expect it to be the strangest day of her life. In a bag ragged by time, she had a checkered notebook, a peanut butter sandwich and a phone with a dead battery. She was jumpy - Mr Dzierżon, the librarian, always looked at new readers as potential robbers. Oskar was already waiting for her in the corner by the window. He had been her best friend since sixth grade, although he had always said that he preferred practical solutions to "unnecessary adventures". This time, however, it was he who persuaded Gaia to search the library together for old maps for a history project. Wandering between the high shelves, they came across a door they had not seen before. It was heavy, wooden, with a large iron key inserted in the lock. Gaia lowered her voice: - Oskar, look! Do you think we're allowed to go in there? Oskar glanced around - no one around. He swung the door open. On the other side there was semi-darkness. The room looked like a miniature museum: bookcases full of yellowed books, globes and maps stood everywhere. In the corner, under a layer of dust, stood a strange clock. Its dial was covered with symbols they did not know, and the pendulum moved slowly, emitting a quiet metallic click with each movement. Gaia walked closer. She touched her finger to one of the numbers carved into the wood. The clock trembled. Oskar took a step back. - 'You'd better not touch it,' he whispered, but it was too late. Suddenly they heard something moving in the wall. A narrow crack appeared on the floor, through which a breath of icy air blew into the room. The books on the shelves began to move, and one of the symbols on the clock lit up with a blue light. - Gaia, what's in there? - Oskar tried to peek through a crack, but then a strange sound, resembling a heartbeat, came from the clock. Gaia felt everything around her spinning. At the same moment they felt a tug, as if someone was pulling on their hands. Before they could react, the world around them disappeared. Their last sight was of blue light and a spinning clock. What awaited them on the other side? Were they still in the library, or were they already somewhere else entirely? The answers were about to come in a moment....