The rain drummed against the glass as Lena, Igor and Michael sat in the school library. It was Friday, and the storm meant they couldn't go home. Mrs Jowita, the librarian, had closed her office, leaving them alone for a while. Lena was browsing through the bookcases, Igor was jotting something down in his notebook and Michal, bored as usual, was looking around the corners of the room. Then his gaze was drawn to a large, old clock standing in the corner of the room. It looked like a relic from the past: tall, with a carved wooden frame, covered in dust. A delicate but massive pendulum dangled from the dial. - Hey, look at that! - exclaimed Michal. Lena went up first and looked at the dial. Instead of the usual numbers, there were strange symbols - something between Roman and completely unfamiliar characters. Igor joined in and looked at the frame. - This clock was here before? - He asked, touching the wood. - I doubt it. I come here every day, but I've never seen it,' Lena replied. Igor noticed a small button just below the dial. It was faded, barely visible, but shaped like an hourglass. - Do you think it works? - He asked, without waiting for an answer. He pressed the button. The clock made a deep, dragging sound, as if it were groaning pitifully. The hands began to turn faster and faster, and the pendulum swung unusually hard, emitting a metallic echo. Around the three friends, the air began to tremble - books clattered on the shelves, lights flickered. Suddenly, everything swirled. Darkness. Silence. When they opened their eyes, they noticed that they were no longer in the library. They were standing on a cobbled street, surrounded by tall tenement buildings with alien signs. The sky was a strange shade, and the din of an unfamiliar city could be heard in the distance. Lena had a watch in her hand, which had previously been lying by the clock in the library. Now the hands moved without any logic, and on its back case was an inscription: "Return only possible when time comes full circle". The three friends looked at each other, and their hearts began to beat faster. From one of the dark alleys came the clatter of footsteps - someone was approaching. They were in a completely different world, and they still had to wait for answers....