In the quiet old school building there was a library, about which there were rumours. Some pupils whispered that strange sounds, resembling conversations and giggles, could be heard there after dark. David had always liked books, but now he was even more fascinated by this place - and not just through the stories of his classmates. He felt that it hid something more than just dusty volumes on the shelves. One rainy afternoon, when most of the children had long since gone home, David stayed in the library a little longer, browsing through atlases and encyclopaedias. The librarian asked him to wait while she finished sorting out the files. David was quietly sitting at one of the tables and suddenly.... noticed that something was buzzing in his pencil case. He carefully opened it - and was stunned. His favourite pencil, the one with the red eraser on the end, started to move! After a moment, he heard: "Hey, do you have something to write with? Because I have an important message for you!" David looked up in disbelief, and then a bookmark with a picture of a cat slid out from behind the book. It winked at David and spoke: - If you want to know the real secrets of this library, you have to trust us. The pencil turned sideways, as if looking around to see if anyone was eavesdropping, and added quietly: - Only today, only now can you enter where no ordinary person has access. You must walk between the bookcases, stop at the oldest book and.... Suddenly, everything around David became strange: the lights flickered and the bookcases began to move slightly, forming a narrow corridor that he had never seen before. There were quiet whispers coming from the depths of the shelves, and the books seemed to glow with a mysterious radiance. - 'Come on, David,' whispered the bookmark, 'it's time for an adventure! David gathered his courage and took the first step towards the corridor, not knowing what secrets awaited him on the other side....