Maks rode his bike to school, rocked on the saddle and contemplated whether today would be his favourite day - pencil case exchange day. It was already a tradition in his class. Everyone collected pencil cases: with crayons, with locks, with cartoon characters or such funny inscriptions. But Maks had an unusual collection - pencil cases that sometimes seemed... alive to him. When he was alone, he would swear he could hear something inside them whispering, creaking and laughing quietly under his breath. After school, everyone rushed home and Maks stayed a while longer. He sat down in an empty classroom and opened his favourite, inconspicuous, slightly scratched pencil case with a yellow zipper. Then he heard a quiet: "Hey, Maks! Alone at last!" He looked around. There was no one there. "I overheard," he thought. But then the zipper of the pencil case began to move of its own accord. "Hello, Maksik!" - came a snarky voice. "I'm Zipper. I've got something interesting for you!" Maks jumped up in his chair. "That's impossible..." he whispered. "Pencil cases don't talk!" "Some do speak, just not when someone is looking!" - giggled Zipper. Suddenly, more pencil cases slid out of Max's bag. A pencil handle slid out of a green pencil case and waved Maks over. "I'm Graphite!" - declared the green pencil case. - "Get ready for an adventure! Things happen at school after dark that you've never seen." Maks twitched with excitement and a little with fear. "What happens at school after dark?" "Shh... Listen!" - Zipper lowered his voice to a whisper. - "When all the people go home, the school turns into a place full of the unusual. Subjects talk, play and... compete! But today... today something is going to happen here." Then a shadow flashed through the ajar classroom door. The pencil cases fell silent, and Maks felt hot. "This is the moment," whispered Grafitka. "You have to come with us. Otherwise... you won't find out what the school subjects are planning. But be careful - some of them don't like nosy people." Maks quietly put both feet on the floor and looked towards the door, behind which movement lurked. Would any of the things dare to show themselves? Would Maks manage to walk through the school corridor full of talking objects and discover what was really going on here? Just then, at the end of the corridor, there was the sound of chairs being moved and a strange light flashed under the classroom door....