There was an item on Nadja's new schedule today that no one could explain. On Wednesday at 5:15 p.m., she was supposed to have "Extended classes: logic" in a room marked with the mysterious letter N. There were no such halls at High School No. 4, only numbers, and the N sounded like a joke. The corridors smelled of chalk and wet jackets, the clock at the gatehouse was always two minutes late. The first week after the holidays had got off to a sluggish start, yet that one window in the schedule was unrelenting. Nadja looked at the printout and felt the paper harden strangely under her fingers. - Maybe it's a shortcut to the new studio? - Kuba asked, hanging his rucksack on his elbow. The porter just shrugged his shoulders and pushed the paper away as if the conversation was not about the building. The e-journal showed the leader: 'M. Nobody', with a message underneath that didn't help. "Please do not be late to room N. Entrance only possible at the designated time." Iga snorted, but a shadow of curiosity could be heard in her voice. - If it's a prank, someone has a knack for detail," she muttered, scribbling the letter N in the margin of her notebook. After the last lesson, Nadja stayed longer because the form teacher asked her to take the forms to the secretary's office. The school emptied in layers: first bells, then footsteps, finally the whisper of the coffee machine. When the clock at the gatehouse indicated 17:07, a sound she had not heard here rang out. It was no ordinary bell, rather a short signal, like from a school radio from another era. A fresh piece of paper appeared on the corkboard, pinned with a red pin, though no one approached. "13N →" - the print was uneven, but the arrow led clearly towards the old wing. Nadja hesitated for a moment and then moved, as if the arrow knew her decision beforehand. The old wing started at the evacuation map, which almost everyone avoided with their eyes. The corridor lengthened with each step, as if someone was adding more tiles exactly under their shoes. Outside the window, the pitch looked different, the snow lay only on one side, and the goal pennant flicked at the wrong angle. The phone had lost range, but it caught a new Wi-Fi network called 'SALA_N', enticingly strong, as if the router was next door. Nadja texted Cuba briefly, "I'm going to check, if anything, call me in five." The message didn't go through, instead a notification from an unsigned app flashed on the screen: "Class is about to start. Don't be late, N." At the end of the corridor, she came across a prom poster from years ago, with yellow tape and a pin. Under her fingers, the paper wasn't flat; something underneath sprang up slightly, like a hidden door handle. She peeled back the edge of the cardboard and revealed a door with a number that no one at the school had ever seen: 13N. The smell of chalk and cold paint drifted out from under the crack, and a barely audible, even whisper came from inside. The whisper didn't form words, but it sounded like her name, repeated to the rhythm of hushed classes. Nadja tightened her hand on the doorknob, took in a breath and before she could press, the handle moved from inside.