It started innocently enough, with the school's Discovery Night and my insistence on staying longer. When most of the students had already left, I was still gathering material for a text for the newspaper. The caretaker, Mr Suchy, turned off half the corridors and threw in a short: "Third floor closed, installation to be repaired." I nodded, although my high school Old Walls was at its most interesting just after dark. Oskar, a fellow journalism club member, held the camera and nervously counted the batteries in the torch. We had stopped by the cup display case when suddenly the bell rang, but not the usual melodious one. A short, uneven series like a signal that someone had put together with pauses and clatters. Oskar is a scout; after ten seconds he muttered: "It's Morse. Three, one, four." And then, as if to reassure himself, the bell repeated the sequence once more, louder. Room 314 lies at the end of the wing, where the walls smell of chalk and floor fluid. The lighting had just been overhauled there, yet a steady white light smouldered from behind the frosted glass. On the door, someone had drawn a simple map with a cross in chalk, like a geography assignment. The cross touched the door handle. "Maybe it's some kind of field game," I whispered, but my throat went dry at the very word game. The door gave way without a creak, as if someone had just let us in. Inside, the benches stood in rows, and on the desk was an old handbell, the one with the metal dome. On the blackboard was a line of even letters: "Leno, find the thing that disappeared before it rings for the last time." Oskar looked around meticulously and pointed to the floor, where three wet boot marks were imprinted, ending at the map cabinet. "Someone was here a while ago," he said, too quiet to sound confident. Before I could answer, my phone vibrated; the sender was shown as the Secretariat, although I remembered that the Secretariat closed at seven o'clock. The message had only one line: "You have fifteen minutes." The clock above the board stopped at exactly nineteen fifteen, as if to mock me. A quiet clatter came from the cupboard and the chalk, left on the gutter, trembled and rolled to the edge. Oskar brought the camera to his eye. "Don't move," he whispered, as the handle to the hall, the one on the inside, began to lower slowly. The handle stopped in mid-motion, as if someone on the other side was contemplating the next step. The light in the classroom dimmed, and a crunching sound came from the speakers in the ceiling, which suddenly formed into a whisper: "Repeat: room three hundred and fourteen." A roll of maps fell from the shelf next to the wardrobe; it rolled, stopping by my shoes like a messenger. Oscar leaned over, but I pulled away as the bell on the desk trembled and struck once, clear and cold. The first time. From inside the wardrobe someone slipped the handle from the lock, though the door remained locked from the outside. On the blackboard, without chalk in a human hand, a new sentence appeared, letter by letter: "Don't look for me in the diary." I tightened my fingers on my phone, which vibrated again, this time without a notification on the screen. From the corridor came the rapid clatter of new footsteps, too light for Mr Dry, getting closer and closer.