Our school smells of chalk even when no one is writing on the blackboard. The old walls hold the smells like secrets, and the corridors are as long as the queue for chips in the canteen. Above it all hangs a turret with a tin helmet - a bell that has been defunct for years, a reminder of the days when lessons started to the sound of metal rather than an electronic buzzer. - 'They said they were going to dismantle it,' muttered Oskar, messing with his head. - They always say things and then it stays as it is. - Don't complain, Oskar - Tamara poked him. - 'I'd rather that than another 'innovation' that only works for the director's presentation. I didn't say anything. It was Monday, the first half of October, and I had three notebooks in my backpack, two pens and something I had found in the library that morning: a small, yellowed piece of paper tucked into an old sky atlas. On the piece of paper, in bullet-pointed handwriting, it read: "When the thirteenth bell sounds, look up." And underneath, a stamp with the letters: "SP 18. Our school. - Lena, are you alive? - Tamara waved her hand in front of my eyes. - History. Mrs Swider is checking the notebooks today. Mrs Świder loved order and clean margins. And although I liked history, I preferred not to check the look on her face when she saw my notes from last Friday, when they suddenly turned off the lights on the whole floor and I wrote in the dark. On the door of classroom 214 hung a freshly printed plan: project week, new classrooms, shortened lessons. Underneath, in small font, something strange had been added. "North Hall - consultation, 12:00-12:15, group A." - What is the North Hall anyway? - Oskar asked, pointing with his finger. - 'We have rooms 101, 102, 103... And not the directions of the world. - Probably an error in the system - Tamara pulled out her phone and logged into the e-journal. - Or a new name for the geography lab. I felt the piece of paper in my pocket getting heavier, although of course it still weighed as much as nothing. Scrawled on it was an eight-pointed star, identical to the one someone had been gouging with a penknife in the wood of the railing next to the stairs to the third floor for years. I always passed it without thinking about it for more than a second. Today it looked like a mark on a map that suddenly starts pulsating. In history, Mrs Swider talked about sundials and how time used to be measured. Oskar was drawing a blind hat for the maths teacher in his notebook, and Tamara was adding missing dates in her calendar. I glanced at my phone every few minutes as the e-journal, against all rules and settings, sent me a notification in the morning: "Reminder: North Hall, 12 p.m. Group: A." I wasn't in any "Group A". At least not the official kind. - Where do you run off to on Long? - we were puzzled by Maja from the bench next to us when the third bell sounded before noon. - The canteen has waffles. - Out in the fresh air - I replied before I could bite my tongue. Tamara looked at me questioningly. Oskar raised an eyebrow. - 'For some very fresh air,' I added in a whisper. - Under the turret. The courtyard was full of noise and laughter, as always at the long break. The pedagogue was circulating with a thermos, the caretaker Mr Rudnicki was adjusting the railings, and the pigeons were pretending not to be afraid of balls. Above it all rose our bell, as if ready to be photographed for the textbook. Up close, we could see that the helmet had dents, and a palm-sized block of wood was broken off in one of the louvre boards, just below the window ledge. - I said! - Tamara has lowered her voice. - 'Look: there's the same thing hanging in the plan - she showed the screen. 'North Hall, 12:00-12:15, start in 1 min'. Next to a bell icon, as if a joke. - And what? - Oskar started laughing. - Will there be a special sound? "Dyyyng-dyyyng, welcome to the North!" - Quiet," I admonished him, although I was also close to laughing. At the same time, I felt a slight current under my skin that made goosebumps on my forearms. The usual school bell is a short, metallic "brzzt" that people ignore or curse. But then, at twelve o'clock, something different rang out over our heads. First a single, heavy thump, as if someone had slapped the air with their hand. Then a second. A third. People began to turn their heads. Someone shouted "Oh dear!". The pedagogue stood up as if she had been struck, the thermos hovered in mid-motion. Fourth. Fifth. Sixth. - After all, this is impossible,' whispered Tamara. - This bell doesn't work. Seventh. Eighth. Ninth. I could hear my heart racing. Each beat sounded like an old book turning a page in drag. Something bright flashed in the broken board under the helmet, maybe dust, maybe a reflection of the sun. The tenth. Eleventh. Twelfth. Everyone in the courtyard fell silent. Even the pigeons. A silence hung in the air as tense as a clothesline pulled across the courtyard. Thirteenth. I didn't know what to expect. Maybe laughter, maybe applause, maybe shouts of "that was a test". Instead, my phone vibrated. "North Hall - class has started. Lateness: 0:12." And underneath, in small print: "Entrance: attic, cage C." - Cage C? - repeated Oskar, looking over my shoulder. - After all, we have A and B. - 'We also have that narrow old corridor next to the science aid store,' said Tamara. - There used to be a door there. - Now there are - I added before I could think. And I knew it was true, even though I had no proof of it other than my accelerated breathing and the trembling piece of paper in my pocket. We had done what one must not do. Instead of going to the canteen, we turned near the art room, passed the display case with the cup for cross-country running from ten years ago and entered a narrow corridor, since I can remember ending with a "Magazine - Do Not Enter" beam. Today there was yellow tape hanging there with the word "Renovation", but it was tied so lightly that it was enough to lift it. Around the bend it was cooler. The walls smelled of dust and apples, like the cellar at my grandparents' house. There was an old map rack in the corner, with a roll of Europe that wouldn't roll anymore. At the end of the corridor there was actually a door. I didn't know them. They were narrow, wooden, with a handle like the entrance to the pantry and with the same sign as on the card and on the railing: a star with eight arms, barely visible under a layer of varnish. - I don't like it,' muttered Oskar. - It smells... well. I don't like it. - It smells of dust and apples - I corrected him. - And the fact that if we don't look, we'll be thinking about it until Christmas. Tamara pressed the handle. The door gave way without resistance and we ascended the narrowest staircase I had ever seen: twisted, wooden, creaking with every step. Light came from small, round windows just below the ceiling, and dust specks danced in the air like stars in a microscope. On the left, on the wall, someone had put their hand down hundreds of times, leaving a dark sheen. To the right, on the first step, I noticed a shoe print in the chalky dust. Fresh. - Someone was here before us,' I whispered. The higher we went, the colder it got. The noise of the school turned into the background, as if someone had turned the volume knob on the radio. Halfway up, an engraved star appeared on the railing again, this time larger, and next to it an arrow and the letter 'N'. - Midnight - nodded Tamara. - 'That even makes sense. - 'Nothing makes sense here,' replied Oskar, but he was following us, and I could hear him breathing faster too. On the next mezzanine was a low doorframe. Someone had crookedly nailed a note to it saying 'Renovation - Do Not Enter', but someone else had written 'Knock Twice' in pencil. Of course I knocked. Once. The second. A pause. A silence that was not silence, but waiting. The phone vibrated again. "North Hall - entrance next door." Indeed, to the right, just above the floor, in a panel of panelling, was a narrow flap, almost invisible. All you had to do was slip your fingers into the niche and pull. The boards clicked and moved back a few centimetres, as if someone had long ago installed a clever mechanism here that uncompromisingly refused to rust. Behind the flap hid an alcove and another door, this time metal, with a round window like in the engine room of a ship. Nothing could be seen through the window, just blackness, smooth as a cloak of night. I grabbed the cool handle. At that moment a whisper came from above. Someone had spoken my name. Not quite a whisper, not quite a voice. It sounded like a sound forming into a word. - Lena. A chill blew in from the secret stairwell. Tamara squeezed the handle of her backpack so hard that her knuckles turned white. Oskar looked at me and then at the door, as if hoping to see some kind of instruction manual on it. Before we had time to say anything, something rattled quietly on the other side of the metal door. Once. A second. The same rhythm as just before on the note on the doorframe. Someone knocked, but this time it wasn't us who were supposed to enter first. The doorknob under my hand twitched, as if someone on the other side had put their hand on it and started turning it slowly, thoughtfully, in exactly the same direction as the one I was holding.