The blue house on Chestnut Street smelled of pancakes and rain. Behind the house grew Old Chestnut, which rustled as if it told stories only for those who could listen. Lila was seven, with freckles on her nose and a braid that always slipped over one shoulder. Franek was five and had pockets full of strange treasures: buttons, sticks, pebbles and rolled-up leaves. With them lived the cat Raven, grey as ash, with a striped tail and tea-coloured eyes. On this day, after the night's rain, the world was fresh and sparkling. Drops of water hung on the grass like tiny lights. Lila and Franek jumped in the puddles and Raven trotted after them, taking careful steps so as not to get her paws wet. "Look!" - whispered Franek and crouched down by the largest puddle. There was a pebble lying at the bottom. It was no ordinary one. It was smooth and blue, as if someone had carved it out of the sky. And when Franek touched it with his fingertips, the pebble was as warm as a fresh roll. The raven tilted its head and purred more deeply than usual. "He... he sings?" - puzzled Lila. Indeed, there was a quiet "mmm" coming from the pebble, like a lullaby one hums on winter evenings. The melody was soft, and with each sound the pebble flashed a faint light. "Maybe she wants to come with us," said Franek, because he believed things had an opinion. Lila smiled, carefully took the pebble in her hand and tucked it into her jacket pocket. She could still feel its pleasant warmth through the material. They entered the attic, where shoeboxes, old suitcases and cobwebs that looked like lace curtains lived. There was also an old chest with stars painted on it. Grandpa said it was a treasure trove of surprises. Lila and Franek often rummaged through it: doll's ears, a coin with a hole in it, a postcard with a train. That day, when Lila opened the lid, the pebble's singing got a little louder. "Listen, he's sort of calling". - muttered Lila. Franek held Mruk so he wouldn't fall into the crate and fall asleep in the old hat. Suddenly, something flashed at the bottom of the crate. It was a drop-shaped piece of glass. When a ray of sunlight fell on it, a luminous mark appeared on the wall. It was no ordinary glare. The trail turned into a thin line that began to elongate, twist and turn, until there was a drawing as if made of mist: a path, a wall overgrown with ivy and something that looked like a small, forgotten door. "It's at our place!" - exclaimed Franek. - "Behind Chestnut, by the wall, there is a door, but you can never open it." The pebble in Lila's pocket rustled sleepily, as if in agreement. The luminous line on the wall trembled and sailed down the stairs. She stopped at the threshold and waited, blinking like a skylight. "I think she wants us to go," - Lila whispered. Her heart beat faster, but it wasn't fear. It was the feeling you get when you open a box and don't yet know what's inside. So they followed the luminous path: through the kitchen, where pancakes were cooling on the table; through the garden, where roses drank the remnants of the rain; until they reached the Old Wall, into which the roots of the chestnut tree had grown. Raven walked with them, adjusting his ears. There really was a small wooden door in the wall. Lila had known them forever, but they had never managed to move an inch. This time, the pebble vibrated and dipped so that you could feel the vibration all the way through your fingertips. A streak of light slipped out of Lila's pocket and sat on the door handle like a butterfly. They heard a quiet click. The door gave way without a groan, as if they were glad someone had come. Beyond the door was a garden that could not be seen from any window. It smelled of mint and wet earth. Leaves moved in the wind, although it wasn't blowing. Flowers rang quietly like tiny bells. Glass drops hung from the branches, shining with their own light, as if they retained a piece of the sun inside. "Oh my," whispered Franek. - "I think this is the garden Mr Gardener was talking about... the one he doesn't have a plan for." In the middle of the garden stood a bark table, round and smooth. Above it hung a lantern made of leaves. As soon as Lila and Franek came closer, the lantern lit up with a soft, warm glow. The raven jumped onto the table and hung its tail in the air like a pole. A book lay on the table. It was not like one from a library. It had a cover of soft leaves, tied with a string of grass. And when Lila blew gently, the pages moved as if the book was breathing. "Do you think it can be opened?" - asked Franek, biting his lip. The pebble in Lila's hand grew warmer. Before Lila could answer, something rustled in the treetops. It rustled the way a basket of papers rustles when you're looking for a drawing in it. Then they heard a whisper. It wasn't scary. It was soft and transparent, as if spoken by someone who doesn't want to frighten a butterfly. "Do you know how to listen?" - the whisper asked. The voice did not come from one place. It sounded in the leaves, in the grass, in the drops of water and in the glass lamps. Lila and Franek looked at each other. The raven murmured a 'yes'. Letters appeared on the cover of the book. Not all at once. First three, and then more, like little ants lining up. A sentence formed: 'If you are ready, knock three times'. "I am" - whispered Franek, but stopped his hand halfway. "Are you?" Lila felt her heart do a hop-hop. She liked adventure, but she also knew that sometimes it was better to take a breath and count to five. She counted in her mind: one - a lantern twinkling like a star; two - the ringing of flowers; three - the warmth of a pebble; four - the softness of a leafy cover; five - a quiet, patient whisper. "I think so," - she said at last. - "But let's listen first." She put her ear to the cover. The book murmured quietly, like a stream under ice. Raven tapped the corner of the table with her paw, as if to say, "Come on." Franek slipped his hand into Lila's pocket and touched a pebble. Melody filled his fingers and spilled down to his elbow. The book pitched itself a tad, like a crab sticking its eye out from behind a stone. A freckled light and the smell of raspberries gushed from within. A drawing appeared on the first page: a slender bridge made of twigs, a small ship made of bark and... a key. The key was not made of metal. It was made of ray. The drawing trembled as if it wanted to pop out of the paper. Something shimmered in the grass. Tiny lights - like skylights, like falling dewdrops - began to line up beside the table. First a line, then a circle, then a tooth. Before Lila and Frank's eyes, on the green carpet of leaves, a shape emerged from the sparks - a key like the one in the drawing. It fluttered like a fish and floated a few centimetres above the ground. "He's moving!" - squealed Franek, grabbing Lilia by the sleeve. The lantern on the branch lit up brighter and the bells of the flowers rang cheerfully and a little impatiently. The book turned the page without being touched, as if a gust of wind knew the alphabet. Three tiny dots appeared and a short sentence: "Now." "I think this is the moment," Lila said. Her hands were warm, but her knees shook slightly. The raven had stopped purring and was staring at the key from the lights. From afar, from behind the wall, came a quiet thud - as if a drop had fallen on the tin canopy, although it was not raining. Franek tightened his fingers on the edge of the table. "Together?" - he asked. Lila nodded. The luminous key twitched and sailed towards the book, leaving a sparkly streak behind. The air became cool but pleasant, as if under a linen curtain. The leaves moved all at once, as if the garden had taken a deep breath. Somewhere above them something bigger than the wind rustled, something that sounded like wings made of rain and light. Lila raised her hand, ready to knock on the cover for the first time. Franek put his finger next to her finger. The luminous key stopped over the middle of the book and began to fall slowly, and a thin ribbon of blue smoke drifted from the torchlight, drawing in the air the outline of a doorway that had not been here a moment ago. The raven wagged its tail, but did not run away. At the same moment, right next to their ears, a whisper whispered something new, so quietly that you had to hold your breath to hear it....