An ordinary maths lesson turns into a trap when 3C discovers the classroom door will not open, the corridor goes silent, and a message appears on the blackboard that no one can explain.
When the final bell cut through the last of Monday's maths lesson, nothing about the room suggested trouble. Chairs scraped back, exercise books were gathered, and Class 3C began its slow, familiar drift toward the door. Susanna tucked her notes into her bag, Adam was still laughing at something Bartek had said, and Julia stood for a moment at the window, watching the sunlit playground below. Their teacher left first, saying something about an urgent call from the secretary's office.
The first sign that something was wrong came when Bartek reached for the handle.
He pulled once. Then again. The door did not even tremble.
"It's stuck," Susanna said, stepping closer.
Bartek planted a hand against the wood and shoved harder, trying to turn it into a joke, but the door stayed shut as if it had been sealed from the other side. Adam tried next, then laughed too loudly when it refused to move. "Maybe the school finally decided to keep us," he said, but nobody laughed with him.
The corridor outside was strangely quiet. No footsteps. No voices. No slam of lockers. Julia checked her phone and frowned. "No signal."
Susanna moved to the window and looked out. The playground was still there, bright and ordinary, yet the sound that should have drifted up from it seemed cut off completely, as though someone had turned the volume of the world down to nothing.
Then the chalkboard creaked.
Across the equations and half-finished examples, a pale blue line began to form, letter by letter, as if written by an invisible hand: Find the object that isn't there before it's too late.
Bartek stepped back so fast his chair scraped the floor. Susanna stared. Adam reached for the board, then snatched his hand away when the writing stayed cold and untouched beneath his fingers.
From the back of the classroom came a burst of static.
The old radio on the shelf, the one that never worked, blinked to life with a weak buzzing crackle. Everyone froze as a voice, barely more than a breath, whispered from somewhere beyond the locked door: "Time is running out..."