Maja, Kuba and Artur, third-year dental students, decided to spend the weekend a little differently than usual. After intensive lectures on periodontal disease, they persuaded each other to take a little trip to an abandoned mine beneath the city, known locally as Fluoride Cave. Legend had it that somewhere deep underground were hidden fluoride crystals that could make teeth shine like no toothpaste in the world. However, older locals warned that 'tooth ghosts' lurked in the darkness - creatures that attacked those who neglected brushing or had something on their conscience when it came to oral hygiene. Equipped with head torches, sonic toothbrushes and energy bars, they entered the cold, damp mine. The corridors were covered in a shiny residue resembling tartar buildup, and there was a disconcerting minty smell in the air. Maja stopped at a rock shelf where someone had carved a mysterious inscription: "For two minutes and no less.... Stick to the rules and you'll come out unscathed." Cuba laughed nervously and took fluoride toothpaste out of his backpack, joking that it wouldn't hurt to be prepared. However, Arthur noticed that their phones had suddenly stopped working. Deeper down the corridor, something flicked - and there was a sound like rhythmic scrubbing. Was it the echo of their own footsteps, or was there really something something was waiting for those who had forgotten their regular dental appointments? Suddenly, from a side tunnel, there was a quiet whisper: "Spit it out if you want to survive..."