Lena, Tom, and Victor find a strange code hidden among library books at Primary School No. 17, and it points them toward room 204, where something unexpected is waiting.
The break bell rang through Primary School No. 17, and the corridors exploded into noise. Doors banged open, shoes skidded on the floor, and voices bounced off the walls. Lena, Tom, and Victor slipped into their usual spot beneath the notice board, still half out of breath.
The maths competition was only days away. None of them said it out loud, but all three wanted to win. Not just for the certificate, either. For once, they wanted to be the ones everyone noticed.
Still, that was not why they were heading to the library.
Most students treated it like a waiting room with books. The three of them saw something better: quiet, hidden corners, forgotten shelves, and the kind of secrets that only appeared when no one was paying attention. Mrs Barbara, the librarian, looked up from her desk as they entered, then gave them the same knowing smile she always did.
"Research again?" she asked.
"Something like that," Tom said.
She only nodded and went back to sorting return slips, as if she had already decided not to ask more.
Victor moved straight toward the nonfiction shelves, scanning the spines with the intensity of someone hunting a clue in plain sight. Lena followed, drawn to a narrow section near the back, where the newer books were packed so tightly they looked untouched.
That was where she saw it.
A small green book, wedged between two heavy volumes on the city’s history. It had no title on the spine, no label they could see. Lena pulled it out carefully and opened it.
The pages were almost empty.
Only a few lines appeared on each one, written in neat cursive: 12F-7, 21A-3, 15D-11.
Tom frowned. "That’s not notes. That’s a code."
Victor was already checking the shelves around them. "Or a map."
They started searching other books in the same section. More marks turned up in pencil along the margins, so faint Lena had to tilt each page toward the light to see them. Numbers. Letters. Tiny markings that seemed random until they began matching them to the library shelves.
Lena’s pulse quickened. "Wait. 12F-7... that’s here."
She slid her hand behind the row of books and felt something thin and hard. A moment later she pulled out a small envelope.
For a second none of them spoke.
Then Lena opened it.
Inside was a single sheet of paper, folded once and covered with just one sentence:
If you are reading this, you already know where to look - but time is working against you. The next step awaits you in room 204.
Tom’s smile faded. "Room 204? Nobody goes there."
"That old classroom at the end of the corridor," Victor said quietly.
Lena stared at the note again. Her skin prickled. The library suddenly felt too still, too narrow, as if the shelves had leaned in to listen.
Mrs Barbara’s chair scraped against the floor somewhere behind them.
Without saying another word, the three of them pushed the note into Lena’s pocket and left the library. The corridor outside was empty, the far end dimmer than it should have been.
Room 204 waited there, door shut, number plate crooked on the wood.
Tom reached for the handle first.
The door swung inward, and a burst of bright light spilled across the floor. A sharp sound cracked through the room, making all three of them freeze.
Behind the old cupboard, something moved.