Olive moved the heavy wooden box with difficulty. It had always seemed to her that the library under the Lindens hid amazing things, but until today she had not found anything interesting. That day she was helping Mrs Celina tidy up a forgotten part of the building. Next to her, with a bunch of post-it notes taped to her trousers, crouched Kuba, her best friend. - Maybe we can find an old treasure map? - whispered Kuba, sweeping the cobwebs from under an age-old bookcase. Olive snorted with laughter. - More likely dust and a piece of cheese for the mice. Kuba squeezed the broom and blinked. - 'Hey, what's that? A dusty brass key protruded from the bottom of the bookcase. It had four strange teeth and a tail curled up at the end, resembling a squirrel's tail. The children looked at it from all sides. - It looks like something out of a fairy tale! - exclaimed Olive. - But where is the castle? They searched the surrounding cupboards until their gaze fell on an old, worn-out sheet by the wall. Kuba pushed it aside with a bang. Hidden in the wall was a small door barely taller than a rabbit. It had a lock with four teeth. Olive felt a shudder. - Do you want to try it? Cuba nodded, inserted the key and slowly turned it. The door squeaked and opened wide. Behind them was a misty, swirling space, full of dim lights. The children exchanged glances. - Are we going in together? - Olive asked, squeezing Kuba's hand. They took a step forward, and the world around them began to change. After a moment, they felt something soft under their feet, as if they were stepping on clouds. A creature with shining eyes and wings of luminous dust appeared in front of them.... The children stopped and held their breath - they already knew that this place was full of surprises, but they had no idea what would happen when the being spoke.