An autumn storm had kept the city busy all day, but in the evening all that was left over Maria Skłodowska-Curie High School was wet air and lights reflected in puddles as in crooked mirrors. The building, as old as the scrapbooks in the school library, smelled of damp chalk and parquet wax. The clock in the hall was showing 19:03 when the bell - the same one that usually set off a wave of noise after the last lessons - rang once more. Briefly, cleanly, as if someone had pressed an invisible button. Lena stopped under the canopy, clutching a small recorder in her hand. She was collecting sounds for a report for the newspaper: the clink of test tubes in chemistry, the creak of the gymnasium door, the whisper of the corridors in the late afternoon. This one tone didn't match anything she already had. "Did you hear that?" - she asked as Michael ran towards her with his bag slung over his shoulder. An analogue camera, once fished out at a flea market, was swinging on his belt. "Sounds like someone would like to invite us for an unofficial consultation." - he smiled. He was in film class, had an eye for framing and a terrible weakness for places where the light is arranged like in old cinemas. The usher, Mr Leszek, stood on the doorstep of the gatehouse and wiped his glasses with a paper towel. "I don't stay after 7pm," - he said, as if it was a physical rule rather than a decision. "The alarm after the storm gets silly. If you want to watch your circle, make it quick. Do you have torches?" Michal lifted the phone, Lena swiped the recorder. Mr Leszek sighed, disappeared for a moment and returned with a bunch of old keys. "Do not enter the C-wing. Closed until further notice. If you need anything, you have my number on the notice board." He hesitated. "And if the bell rings again... don't respond. It's probably a short circuit." The corridor welcomed them with a silence that was not the absence of sound, but a thin sheet of it. In the cup display case, the hazy glass reflected their faces in broad smiles from years ago. On the walls hung prom posters from which letters were slowly falling off. The puddles under their shoes smeared into long tongues. "Room 204, physics. That's where the echo catches best," Lena nodded towards the stairs. Below, beneath the steps, a single motion button still trembled, to which the emergency light strips responded. The door to 204 was ajar to the thickness of a hand. Inside, the demonstration table smelled of dust and unforeseen experiments. On the blackboard were half-removed diagrams from Mrs Grot's last lesson, but what immediately caught the eye was the clock above the door. The second hand was slowly going backwards like a reverse movie. Tick-tock-tick-tick - to the left. "Are you kidding?" - Michael leaned against the angle of the camera, checking to see if it was an illusion. "No. And don't tell me it's an attractive special effect, because I just got the shivers." - Lena activated the recorder. The light blinked green. A journal lay on the desk. The open pages were yellowing at the edges, and someone had hurriedly put a cross next to the date October 2001. Under the list of names, Lena's gaze stopped abruptly. In row thirteen - her name. Lena Kosinska. The same handwriting used to enter the rest. The same swirls next to the "L". In the same ink. "This is... impossible." - she whispered. "See." Michael stepped closer and didn't have time to reply when the school's radio station whirred like an old radio. The speakers along the corridor lit up with a colourless hum. "Attention, attention," came a male voice, clear and soft, a stranger. "Class 3C, please join us in room 204 for extra classes. Please be on time." Lena looked at Michal. "After all, Mrs Biernacka has a completely different voice," she hissed. - "And 3C existed twenty years ago." Something clicked in the loudspeaker, as if the microphone had fallen over the edge of the table. Then the bell rang once, just once, clear as crystal. Not from the corridor. From downstairs, from inside the building. On the cork board by the hall's exit hung an old map of the basement, closed with a pin. Someone had put an arrow in pencil, thin as a spider's thread, and written in the corner: For duty 3C - today only. Behind the map, between the frame and the paper, was an envelope. Lena slid it out carefully. Inside she found a heavy key with a tarnished tin: S-0. "Basement?" - Michael already knew where that letter and number led. Behind the biology room, in the oldest wing, there was a door that, even during evacuation attempts, was bypassed by sight. Never opened. "I don't think we should," - Lena said, though her hand clenched tighter on the key. "Mr Leszek said..." "That the alarm was whirring. And the key? It was waiting for us." - replied Michael quietly. "See. Everything seemed to be expecting us to come." The stairs to the basement fell underground in a gentle curve. Pipes dangled from the ceiling, on which water had condensed after the storm. To the left, behind the dirty glass of the cloakroom window, were umbrellas left by someone long ago. The emergency lights glowed with milk. Every step echoed too loudly, as if the walls liked to repeat people's words. The S-0 door looked different from the rest: metal, with a fine network of scratches where someone had once slipped chalk and tried to rub it off. A plaque with the faded words ARCHIVE hung above the handle. A shiver ran under Lena's skin, not at all from the cold. The radio station buzzed again, shorter. The clock upstairs - somewhere in room 204 - was ticking backwards. The corridor smelled of ozone and paper, which had absorbed the smells of all the interruptions over the years. Michael put his hand on the doorframe and nodded. Lena lifted the key. The metal, though cold, seemed to pulsate to the rhythm of their breaths. She brought it closer to the lock, and then, on the other side of the door, someone very quietly, quite clearly, knocked.