Nina stared in disbelief at the huge oak tree, spreading a dense shadow over the schoolyard. Her first day at Primary School 17 was stressful in itself, but did there have to be such an eerie atmosphere here? The tree looked as if it remembered a time when dragons still walked the world - its branches were thick and its bark ragged with the marks of invisible claws. There were other first-graders hanging around the school, most with their phones glued to their hands, trying to take a selfie under the "legendary" oak tree. Nina, however, sensed something more than just the smell of damp leaves in the air. It was like a quiet whisper one hears under one's eyelids just before falling asleep. - 'That tree is a scuffle,' muttered Ala, Nina's new bench-mate, fearlessly approaching the thickest bough. - They say that someone once disappeared here on the night of the summer solstice. But that's just gossip! Nina wasn't so sure about that. Reflexively, she reached into her pocket, where she had a small notebook. Lately, she had had the feeling that by noting down strange phenomena, she was attracted to more and more of these inexplicable events. The bell rang to announce the start of the practical magic lesson. At least, that's what it stood for in her plan, though she thought it was a joke. A teacher was already waiting in Room 207 - tall, slim and rather of those who could cast a shadow even in the dark. Mr Ruczaj greeted the class with an impenetrable smile. - 'Welcome among the Shadows,' he said. - Today we will learn how to spot the hidden. Although... not all of you will want to see it. Nina felt a pencil tremble in her notebook. She opened the notebook and tiny letters appeared on the page: "Watch out for the shadow under the oak tree." She glanced at Ala, who had apparently noticed nothing out of the ordinary. Mr Ruczaj moved between the desks, and the air in the room began to thicken. Music reminiscent of rustling leaves was gently drifting from the speakers. Suddenly, the light in the classroom dimmed and the shadow of the tree in the courtyard began to move, slowly creeping in through the open window. Nina froze as she saw the long dark shape glide along the wall at blackboard level. The teacher smiled even wider and said: - It's time for you to see what's really hiding in the shadows.... At that moment, the shadow extended something like a hand towards Nina.