Lena and Philip find a hidden door in the abandoned industrial park and follow a faint mint smell into the old underground. Something is still running below, and someone else is already there.
Until a few months ago, Lena was sure her life was destined to stay small and predictable: school, skateboarding, and maybe one dramatic train ride to a neighbouring town if she was lucky. Then June arrived, Philip got bored, and they rolled their boards into the abandoned industrial park on the edge of town.
The place looked harmless in daylight, which almost made it worse. Wild grass had swallowed the cracked paths, the windows of the old warehouse blocks were black and empty, and the air carried that stale, metallic smell of places everyone had agreed not to talk about. People said homeless men slept there at night. People said there were lights underground after midnight. People said plenty of things when they wanted to make a ruin feel bigger than it was.
Lena and Philip had another reason to be there. The two of them had been living on sweet cola for months, and the dentist had already started sounding disappointed every time one of their names appeared on the schedule. Their class had turned decay into a competition, as if shame could be measured in fillings.
Philip swerved around a patch of nettles, his wheel clipped something hidden in the weeds, and the ground answered with a heavy metallic thud.
He froze. Lena did too.
They crouched together and pulled back the grass. Beneath it was a rusted trapdoor, half buried in the earth, its edges crusted with old grime. A logo had been stamped into the metal: a wide grin and a toothbrush crossed like a warning sign.
Lena stared at it, then gave a short laugh that sounded too bright.
"I think that's from that toothpaste factory," she said. "The one our parents used to talk about before it went bankrupt."
Philip was already fishing his phone from his pocket. He switched on the flashlight and knelt by the lock. It looked ancient. It also looked wrong, like something that had been opened more recently than it should have been.
The latch was not locked.
They exchanged a look, the kind that says no and yes at the same time, and Philip pulled the door up. The hinges complained in a long, thin squeal. Cold air rushed out from below, carrying a smell Lena couldn't place at first. Damp concrete, dust, rust.
And mint.
Not toothpaste from a shop. Something sharper. Cleaner. Alive.
"You first," Lena whispered, though her voice was barely there.
Philip grinned, but it didn't quite hide the tension in his face. He aimed the light down into the dark gap, and together they climbed into the tunnel.
The passage swallowed their footsteps. On both sides, old machines crouched beneath sheets of grime, their metal bodies marked with fading labels and peeling hazard signs. Sacks of powder were stacked against the wall, and every few metres a poster still clung to the concrete, all bright smiles and impossible promises.
Then Lena heard it.
A sound so faint she almost mistook it for the blood in her ears. A hum. A low mechanical pulse, coming from somewhere deeper inside the tunnel.
Philip stopped walking. "I thought this place had been dead for years," he murmured.
Lena didn't answer. Ahead of them, the corridor narrowed into another chamber, and beyond that, a steel door leaked a pale strip of light across the floor. Someone had hung a note on the handle in neat black ink:
Entrance only for those who know the true power of clean teeth.
Lena reached for the paper before she could stop herself. The message was still warm.
Her neck prickled.
The hum on the other side of the door grew louder, as if whatever was inside had just noticed them.
Then, behind them, came the soft sound of footsteps in the tunnel.