During renovations at High School No. 7, Ola and her friends notice a sealed-off floor, a missing office, and a key that seems to open the wrong door.
When Ola walked into High School No. 7 that morning, the building felt wrong.
It was still the same place with its chipped paint, loud radiators, and the stubborn creak in the third step of the main staircase. But the entrance was packed with restless students, and a bright yellow banner had been stretched beside the portrait of the first principal: ATTENTION! RENOVATION! SORRY FOR THE INCONVENIENCE. For once, the school looked less sleepy and more alive, as if something under the peeling walls had finally been disturbed.
She spotted Kacper and Maja near the lockers. Kacper was already filming the corridor barriers on his phone, grinning like the whole day had been arranged for him. Maja was standing with her notebook open, listening to the janitor as he marched past everyone and repeated, for the third time, that nobody was to go upstairs.
"Have you heard?" Maja asked as soon as Ola joined them. "The builders found something on the second floor."
"Like what?" Ola asked.
Maja shrugged, but her eyes were sharp. "Nobody’s saying. Mr Adam from chemistry couldn’t even get into his office."
"Maybe they finally found the source of the roof leak," Kacper said. "About time."
The warning from the janitor should have been enough. It wasn’t. By the end of lessons, the three of them were standing at the taped-off stairs, watching the empty stretch of corridor above them and pretending they were just curious, not tempted.
"We’re only looking," Maja whispered, and before either of the boys could argue, she ducked under the tape.
Ola followed.
The second floor was darker than it should have been. One fluorescent strip buzzed above their heads, flickering over the closed classroom doors. Somewhere at the far end, workers were talking too loudly to notice them. The corridor leading to Room 24 looked abandoned, almost swallowed by dust.
That was when Ola saw the key.
It lay under the windowsill, small and heavy, the metal dulled by rust. She picked it up before she could think better of it.
"Well?" Kacper said, stepping closer. "Looks like it belongs to something important."
Maja was already at the half-open cabinet at the end of the hall. Through the glass she could see a faint reflection, a strip of light where there shouldn’t have been one at all.
Ola looked down at the key in her hand.
Then footsteps broke through the silence behind them, fast and hard on the stairs, and someone said, very quietly, "What do you think you’re doing up here?"