Ola ran her fingers over the rusty handle of the attic door. Holidays in her grandmother's old tenement had long ceased to be an attraction, but today, for the first time, she noticed a mysterious sign by the doorframe - a compass-like drawing with three arrows and twisted letters. Cuba, her younger brother, was standing behind her and munching a rusk, watching her every move carefully. - Hey, look! I think it's some graffiti,' he whispered and moved closer to see better. - Do you think it could mean something? Ola shrugged her shoulders, but her heart was beating harder. She had always been drawn to strange nooks and crannies, and the old attic evoked something like a thrill of excitement and something intangible in her. The door creaked and opened reluctantly, letting in air that smelled of dust, old books and the shadow of cobwebs. Inside, light leaked narrowly through a small window, casting geometric shadows on the floor. The attic was not so ordinary, however - a pile of old diaries lay against the wall and a clock without hands stood in the corner. On the floor someone had spread out an unfinished game board. Every detail seemed to be waiting to be touched, as if no one had bothered them here for years. Kuba crouched down by the board. - Look! There are some pawns here, but they look like .... miniature versions of us. - He picked one up and looked at it carefully. - You, she even has your glasses. Ola felt a strange mixture of anxiety and excitement. She reached into her pocket and took out her sketchbook - she suddenly felt the need to make a note of everything in here. Against the wall, she spotted a door they hadn't seen before. It was tiny, barely knee-height, but perfectly made, with a small brass handle. Cuba's eyes lit up. - Let's open them! - he whispered, as if afraid to frighten away the hidden thoughts of the place. Ola knelt down and gently pressed the handle. The door gave way with a quiet click and suddenly a glow of coloured light burst from inside. Inside, however, there was no storage compartment, but a tunnel that rippled and disappeared into the depths like a river of light. - Can you see it? - Ola looked at her brother, who stood beside her stunned. Images moved down the tunnel: levitating islands, birds with three wings and cities made of letters, as if the world of imagination really existed, just waiting behind that door. A sound came from the side of the board, as if the pawns had moved one field by themselves. Scraps of paper swirled in the air and a clueless clock suddenly made a deafening sound. The attic trembled, the light in the tunnel pulsed more intensely, and Ola felt as if something or someone was waiting for them on the other side. Cuba squeezed her hand, ready to continue the journey - or retreat. Would they cross the threshold of worlds?