It all started on a cold, foggy evening as Lena walked home alone after her drawing class. Her town, though unassuming, had something understated about it; cracked pavements, old-fashioned street lamps and whispers of history lurking at every corner. Lena stopped when she noticed something odd - in the gap between the tenement and the abandoned kiosk, where there should have been just a dead end, there was a cast iron staircase leading down. The door of the underground station was open. She had always had a vivid imagination, but what she saw looked all too real. There was no doubt - the stairs were inviting. She descended slowly, feeling the chill beating off the walls. The room below was lit by smoky lamps. A silvery train stood on the platform, and the electronic destination board displayed only one sign: "Interworld - Transition Station". There were other young people sitting on the benches - some talking in whispers, others looking ahead with an absent expression on their faces. Lena felt a strange sting of curiosity and anxiety at the same time. Everything in this station seemed suspended between dream and waking. Someone handed her a ticket. An unfamiliar boy with amber eyes looked at her intently and said: "Only those who are not afraid of their own imagination can go on." Before she had time to think, Lena entered the carriage. The door closed behind her, the light went out for a fraction of a second, and when it came back on, there was no longer a city outside the windows. Space rippled and the landscapes changed with every passing moment - fields full of drifting planets, forests where the trees had leaves made of mirrors, bridges of light thrown over the endless darkness. Suddenly an announcement came from the loudspeaker: "Next station: the Threshold of Imagination. Disembarkation only for the brave." Lena held her breath, the train slowed down, and as the doors began to open, she felt something - or someone - waiting for her on the other side....