No one at the school was interested in the fourth floor. Maybe because it didn't officially exist - the building plan ended at the third, and the staircase behind the big shiny door was always locked with a thick iron chain. However, Lena knew her own. She found an entry in an old reader's diary from fifty years ago: "Room number zero. Whoever dares to enter will see what the mind cannot encompass." The next day, right after lessons, Lena chatted to Nikolai and Zuza. They trusted her, because Lena never threw words to the wind. The three of them made their way to an inaccessible part of the corridor, taking advantage of the moment when the janitor was asleep by the radio. To their surprise, the chain was cut this time. The door gave way and a staircase led upwards into a dark, dusty corridor whose walls were tightly lined with mirrors. Each mirror reflected something different: once themselves from before, once not their face at all, once the inside of a room with an unfamiliar book on the table. At the end of the corridor, a dark door with ZERO written on it waited. Lena hesitated, but Nikolai whispered: "After all, that's what we were looking for." As she pressed the handle, a shiver ran down her spine. Inside, there was impenetrable darkness, but the smell of paint, paper and thunderstorms lingered in the air. Suddenly, the light from the corridor began to tremble, and a luminous circle appeared on the floor, in which lazily floated... letters. Each swirled, merged with the others, creating vivid images in the air: cities built of chocolate, dragons flying through clouds, the shadow of someone's smile. Zuza reached out her hand to touch the flickering word "DARE". Then something moved in the depths of the room, and a whisper echoed: "Come in, if you can stop being yourself..." Outside, a door suddenly slammed and the corridor disappeared. Were they prepared to walk through the portal of imagination, not knowing if they would ever return?