tight, "nobody move."
For once, even Jayden lowered his ruler microphone. The chalky creature crouched on the desk, its black minus-sign eyes sweeping across Year Nine like it was choosing who to erase first. Red-pen crosses crawled over its dusty arms. Its bracket-like teeth scraped together, and its rusted mouth opened with a sound like a pencil sharpener eating a spoon.
Then it spoke.
"Holly Downey," it said.
Holly went cold from her blazer collar to her shoes. The voice was not dusty or gobliny. It was warm, tired, familiar. The voice that used to call, "Feed Ben and Geri before they form a cat union."
"Mum?" Holly whispered.
Orla grabbed her hand under the desk. "Hol, that is not your mum. That is literally a haunted maths bogey."
The Miscalculation smiled wider. "Every mistake has mattered. Every wrong answer. Every crossed-out working. I nudged them. Bent them. Steered you all here."
Mr Tafadar stepped in front of Holly, medium brown face serious, dark eyes fixed on the creature. "You do not use a child’s grief as a teaching aid."
"Aww," Callum muttered, "Sir’s gone full final boss."
The goblin slammed one chalky fist down. Exercise books jumped. "Under this school is the city of gears. You have been solving your way to it since September."
Milo looked personally offended. "I knew question six was suspicious."
Tia leaned to Megan. "If there’s an underground city, I’m not going unless the lighting is flattering."
Sana, who was super nice even during magical disasters, slid Holly a highlighter like it was emotional support. Priya whispered, "For courage. Also it’s pastel."
The Miscalculation lifted its arms. The floating wrong answers twisted into an arrow pointing at the classroom door.
"Down where the lost sums tick, the corrected hour will click."
"Absolutely not," said Mr Tafadar.
The floor under his desk cracked.
"Slightly not?" Reece suggested.
⁂
They ended up in the basement because the corridor lights began blinking arrows, the stairs folded behind them, and the Miscalculation chased anyone who tried to run the other way. Mr Tafadar kept everyone together, barking, "Pairs! No heroics! Jayden, stop narrating your own panic!"
"Viewers, the maths villa has taken a dark turn," Jayden said, jogging backwards.
Holly stayed close to Orla, heart banging. If that thing knows Mum’s voice, maybe it knows where she is. She hated the hope as much as she needed it.
In the basement, old chairs were stacked like skeletons. The air smelled of damp paper and forgotten PE kits. The chalk arrow pointed to a patch of concrete covered in tiny carved numbers.
Arun crouched. "It’s a sequence."
Bea squinted. "It’s also a floor. Let’s not flirt with doom twice."
But Milo, Sana, Priya and Holly solved the pattern together, calling numbers while Mr Tafadar watched the goblin. When Holly said the final answer, the concrete cracked open in a perfect circle.
"That," said Lacey, "is not on Sparx Maths."
The floor collapsed.
⁂
They landed on a brass platform above a vast city buried beneath the school. Towers of clockwork rose into darkness. Streets of gears turned by themselves. Tiny windows glowed gold. Bells chimed from nowhere, and across every roof, number wheels spun faster and faster.
Holly stared. "It’s awake."
On the nearest tower, a giant clock face clicked from 00:10 to 00:09.
The Miscalculation dropped beside them, laughing in Holly’s mother’s voice.
"Welcome, children," it said. "Correction Day begins when the countdown ends."
Mr Tafadar lifted one arm to shield the class.
Then every clock in the city turned its hands towards Holly.
