The storm moved over the city like a great, sleepy whale. Thick raindrops were hitting the roof tiles of an apartment building on Dove Street, and the narrow courtyard was filled with the smell of wet dust and lime blossoms. Lena stood by the attic window and drew a droplet with her finger as it raced down the glass with another. Next to her, Olek was holding a shoebox, and sticking out of the box was a long, unevenly wrapped roll of paper. Screwtail the cat, as patchy as a map, wriggled between their legs and occasionally said "mrrr" in a way that sounded like a question. - 'Mum said we could put the old utensils in order before Mr Gregory came,' Lena recalled, wiping a smudge from the glass on her jeans with her finger. Her mum was the administrator of the tenement and every Tuesday she checked that the guttering wasn't leaking anywhere and that someone hadn't eaten Mr Gregory's coffee by mistake. - And that nothing was thrown away without being asked. - And if we find something great? - Olek shook the box impatiently. - Something that works? The boxes, boxes and boxes from the loft looked like little houses of crumpled cardboard. On one was written "ribbons - don't bite!", on another "lights - they don't glow, but nice". Between them stood a tall, narrow bookcase hidden in cobwebs. Lena blinked as she saw something animated on the shelf in the lightning - it turned out to be just a piece of rope that had moved from the draught and fallen like a lazy viper. - Look at this - Olek crouched down by a small wooden trunk. On the lid was an inscription: 'Storm Chalk - draw when you hear thunder'. - I think it's a joke," he added, but his eyes lit up the way someone's eyes light up when they know they're going to try it anyway. Lena opened the trunk. Inside lay chalks in metallic shades: dark blue like night, green like moss, silver like water when the sky is cloudy. Each chalk was wrapped in a thin strip of paper with a microscopic drawing - a pinwheel, a drop, a star. One, thicker, had a handle drawn on the paper. - A handle? - Lena touched the drawing gently. - Maybe it's from some sort of theatre set. Or... - she suspended her voice, because at the same moment there was a long thump that rolled down the roof and into silence. Bolt raised his tail and shook his ears. Boom. Boom. Boom. A flash of lightning ignited all the hens in the air for a moment, like tiny golden sparks. - 'Draw when you hear thunder,' Olek repeated in a whisper. - 'So... shall we draw? The attic had one wall so smooth and white that it begged for a drawing. Lena squatted down by it and picked up a chalk with a handle. The line was fleshy, leaving a shiny trail behind it, as if someone had glued a thin sheet to the plaster. As she chalked out the rectangle, the drawing began to smell unexpectedly. Not dust, not chalk - just wet moss, needles, the promise of coolness. - Can you smell it? - She asked, without taking her eyes off the wall. - The forest - said Olek as seriously as if he had just recognised the voice of an old friend. - The kind after the rain, when everything is soft. Lena drew the hinges. At that moment the chalk trembled, as if a distant echo had touched the tip of her finger. Bolt jumped onto the pile of books and tapped the silvery line with his paw. The outline of the door shimmered, and something she was sure she hadn't drawn appeared in the middle of the rectangle - a delicate, oval protuberance, like a peephole. Lena held her breath. - It's getting a bit... real, isn't it? - Olek scratched the back of his neck to hide a shudder. - 'A bit,' Lena admitted. - Do you hear that? - She added after a moment. From the other side, although there was only a wall after all, a quiet sound came to them, like the clink of china or distant bells hidden in the grass. Then a whisper, soft enough that it might as well have been the wind dragging across the letters 'Storm Chalk'. - Hello? - Lena leaned into the drawn peephole with her head bowed. - 'Is there anyone there? They both laughed at their own seriousness. It was that nervous, brave laugh when you do something for the first time and pretend it's nothing. - Wait - Olek walked over to the bookcase and started looking through the jars of buttons. - If this is a door, we need a key. - When he said this, he was surprised himself: where did it come from? It was as if someone had put the answer in his mouth. - 'This one doesn't have to be opened with a key, it has to be opened with a handle,' Lena pointed to a drawn, silver handle, which suddenly moved a shadow away from the wall, as if it was really sticking out. But before she could touch it, Bolt did something cats do when they feel someone is about to forbid them something. He jumped down from the books, ran over a roll of paper, slid like he was skating on the dusty floor and jabbed his paw right in the middle of the drawing. His paw... disappeared. Not so completely. It just went inside, as if the plaster was as soft as pudding. The lines trembled and spread a millimetre apart, creating a cool, shiny gap. Bolt withdrew his paw, licked his fur and looked at Lena with a look on his face: "Do I really have to go in first? - Not allowed! - groaned Olek, but he sounded more curious than frightened. Lena carefully touched the drawn handle. It was cool and a little rough, like a pebble from the river. At the same moment, a fresh breeze swept through the crack. She felt drops on her skin - not water from the roof, but mist, as if someone had swiped a dew-covered branch. Somewhere very close by, beyond the wall, a bird they had never heard before rang out. Its voice sounded like cracking ice, and immediately afterwards like a guitar string. - 'If that really is a door,' Lena said slowly, 'then I think it's calling us on its own. - What if it's just a drawing that smells like a forest? - Olek tried to be reasonable, although his fingers trembled like compass needles. Then something fell. Not in their world - in that world. A gentle clatter, like a knife falling on the wooden floor. And then... three short knocks, clear, emphatic. One. Two. Three. Lena and Olek froze, each with his hand right next to the drawn handle. Bolt curled up in a ball and pretended not to care, but the tail said otherwise. The weiss-like tip nervously hit the floor again and again. - Can you hear the rhythm? - Olek tilted his head. - It's that old signal you used to call the guard on the bridge in the game I always lost. Do you remember? Lena remembered. Two short ones, one longer. But now they were even and accurate. One. Two. Three. After each knock, the invisible air vibrated, like a sheet of water after a pebble had been thrown in. - Maybe it's someone who also draws? - snapped Lena out. - 'Or someone who doesn't know how to go back,' added Olek quietly. The rain accelerated, as if the sky had decided to practise drumming its fingers on the roof. Another bolt of lightning flashed above them and for a second the drawing on the wall looked as if it had depth - real, dark, with a distant, silvery light. Olek looked into Lena's eyes. In that look was: "We're just as scared, but we're going together." - On the count of three? - Lena asked. - 'On three,' replied Olek, encompassing the door, the chalk, the cattails, the whole whirlwind with his eyes. They counted off in a whisper. One. Two. Lena's hand tightened on the cool, drawn handle. - Three. The handle moved of its own accord.