When Nikodem, Patrycja and Dawid decided to go truant, none of them imagined that this simple escape from lessons would turn into the adventure of a lifetime. Sitting on the steps behind the gymnasium, Dawid mindlessly picked at a crack in the concrete floor with a stick until suddenly a large piece broke off. - Hey, look! - he called out, leaning over the resulting hole. All three of them heard a muffled noise, as if someone was vacuuming, only ten floors above ground. Nicodemus leaned further over and threw a coin inside. Instead of a deafening clatter, a quiet crunching sound reached them, followed by a a quiet brushing sound. - Strange... - Patricia furrowed her eyebrows, - This is no ordinary cellar room. It didn't take long to persuade them. Nicodemus pulled out his phone and switched on the torch. They had moved the curtain of ivy vines and could now clearly see that there was an entrance to something like a tunnel at the point of the floor. It was constructed of ... glassy white 'bricks' and shone with the light reflected from their phones. As they followed the tunnel, they couldn't help but notice that the walls smelled of fresh mint. Coloured lights glimmered in the distance. When they reached the end of the corridor, they saw a speeding street of an underground city, in which instead of cars there were... electric toothbrushes. electric toothbrushes. - Are we dreaming? - whispered Patricia. David, however, did not wait for an answer and approached the nearest kiosk where a strange gentleman resembling a tube of toothpaste was sitting. - Welcome to Zębopolis! - The tube-like salesman smiled broadly. - We are about to start the Clean Gums Tournament. If you have come to save the City from the scourge of the Stone Jaw, you must earn your brush badge! Loud shouts and the sound of sirens came from the street. There was excitement in the air and a slight hint of danger. All around were the townspeople flitting about: gels, dental floss, mouthwash and.... one, very hostile-looking, black toothbrush. - 'Follow me,' said a strange, silvery thread suddenly, which wrapped itself around their hands. - 'You must act quickly. The Stone Jaws already know you are here. You will soon meet them on your own path. Nicodemus looked anxiously at Patricia and David. There was no turning back now. Toothopolis was waiting for the heroes. Just then, an ominous thunder sounded in the distance and a wave of grey dust swept across the main square, shaping itself into the silhouettes of the Stone Jaws....