The high concrete walls of Copernicus High School glistened in the faint light of the late spring morning. Kuba, as usual, arrived by bike a few minutes early, leaning over his phone at the entrance. He was waiting for Maja, who was rarely late, and for Igor, the eternal dreamer and newest member of their pack. He liked these mornings, when the school was still asleep and the corridors were empty and somewhat intimidating. Little did Cuba suspect that this would be the first day that would be etched in his memory for a long time. As he approached the cloakroom, he saw two girls from the younger class standing motionless by the door, staring at something in horror. When he stepped inside, he was stopped by a cool breeze, as if someone had opened a window - although, after all, they were all locked. At his locker he came across Maja. Her face was grim and she was holding a piece of paper. - What is it? - he asked quietly. Maja handed him the piece of paper. Her hands were trembling slightly. Cuba read: "Not everything is what it seems. Look under your own feet." - Is this some kind of silly joke? - he whispered nervously. - 'I wasn't the only one with a note like that,' said Maja. - They were found in several cupboards this morning too. Igor joined them, looking more intrigued than frightened. - Maybe someone's making a play for the midterms? For the next few hours, the students whispered among themselves about the cards. The atmosphere thickened, every creak of the floor and slight breeze aroused anxiety. At the long break, Kuba, Maja and Igor decided to investigate on their own. They entered the oldest wing of the school, rarely visited by pupils. There, they noticed another piece of paper, stuck to the notice board. This time there was only a strange drawing on it - the outlines of something resembling a door with a barred window and an arrow pointing towards the library. Kuba's heart beat faster. This place had been avoided even by the teachers, ever since the old caretaker had talked about the strange sounds coming from the locked rooms. But today, instead of being overwhelmed by fear, they felt an irresistible urge to see what was behind the library door. Quietly, so as not to attract anyone's attention, they approached the patterned wooden door. It was ajar. Inside was semi-darkness and the smell of old books was in the air. Igor whispered: - It's now or never. Kuba pressed the door handle and all three of them slipped inside. Behind the bookcases, almost in the middle of the room, they saw a strange boy with a face completely alien to them. He stood in a motionless pose, as if waiting for them. He smiled and nodded for them to come closer....