The city after the storm smelled of wet brick, leaves and a freshness that makes even an ordinary pavement look like the start of a trip. Lena stopped at the top of the stone steps leading up to the old arched bridge. Water dripped from the railings like metal whiskers, and the deepest puddle reflected two lanterns and a patch of sky on which hung a bright daytime moon. - "Library Under the Wet Bridge" - read half aloud to Olek, who always read first and thought later. - Sounds like a place where books wear wellingtons. - 'Come on, before the sun dries out the stairs,' said Lena. - Rain is the best weather for discoveries. They were neighbours and friends, of the kind that can be silent next to each other and hear the same thing. Lena was eleven years old and had pockets full of strange trinkets: feathers, buttons, a candy glass. She collected words, noted smells, touched anything that made a sound. Olek was ten years old and collected screws (each one had a name), and gears and plans in his head. Together they made maps of things that no one normally maps: the route the postman's cat takes; the places where puddles hold the sky the longest; the benches that creak like lock doors. The library door was low and green, with a drop-shaped bell. When Lena swung it open, the bell chimed as if someone had tapped the porcelain with a spoon. Inside, it smelled of tea, paper and a light mist. Shelves piled up to the ceiling, but they weren't ordinary: some had railings like bridges, some had ladders, and some had drawers signed in writing so fine you had to read it with a magnifying glass. The floor rippled softly in several places, as if a quiet river flowed under the boards. - 'Welcome rainy visitors,' a warm voice called out. A lady with hair pinned up in a high bun that was held in place by two pencils slid out from behind the counter. Her name was Mrs Tatarak, which fitted the place as well as a puddle to the pavement. Her moss-coloured shawl was finished with tassels pretending to be grass. - In this library, books are best read when the weather feels like water. Do you have wet shoes? Perfect. - Are there atlases here? - Olek asked, rubbing his glasses with his sleeve. - The kind that show not only roads, but also ideas? - There are - Mrs Tatarak nodded. - But remember the rules. Firstly: we don't tear anything out. Second: we don't dry anything on the radiator. Third: we don't feed the paper fish. And fourth, most importantly - she showed with her finger a placard nailed to the counter. On it was written: "Maps like to be touched by someone brave and kind". - Understood? Lena and Olek nodded their heads seriously, although smiles lurked under their skin. A shelf of atlases stood in a niche where drops from the bridge tapped against the stone with a steady rhythm. Above the shelf hung a clock with a dial on which, instead of twelve dashes, there were thirteen. The hands moved like pointers, but the shadow of the hands flowed in the opposite direction, which delighted Olek. - This would be useful for our maps,' he mused. - A shadow that doesn't snort like a cat. Lena looked through the spines of the books. One was upholstered in canvas the colour of a stormy sky and was titled 'Atlas of the Roads That No One Knows'. Lena's fingers, though usually warm, felt suddenly cold, as if she had touched a mirror of water. - 'This one wants to come with us,' she said, and the book, as if in response, emitted a quiet chill. They sat down at a round table whose top was like a koi in a pond - red, with black dots. Mrs Tatarak brought them each a cup of brew: 'Rain chamomile,' she announced, laying down spoons that buzzed like mosquitoes, but pleasantly. - I'm going to get the shoe towels," she added, disappearing between the shelves. Lena gently unfolded the heavy cover. The first page was clean, but there was a sentence written in pen in the corner: 'Read only in the rain'. On the next - a map. It was not ordinary. The lines of the roads rippled as if someone had drawn them on the surface of a lake. Each bend had its own colour, and the street names changed colour depending on who was looking at them. Lena brought her face closer. The letters trembled like drops on a windowsill. - 'Look,' Olek put his finger next to the corner signed 'Almost-straight'. - After all, that's our bridge! - Together they recognised Brzegowa, Sock Street (someone once lost all their laundry there), even the café where they serve raspberry dumplings for the brave. It was just that in addition to the well-known places on the map, there were some they had never seen: "Street Up and Down", "Forgotten Steps Square", "Question Box" and something that looked like a small, blinking point signed in small writing: "The Window in the Puddle". - Have you never seen a street like this? - asked Lena, although she knew that Olek knew streets like letters of the alphabet. - No - Olek moved closer. - But this spot flashes. See? It can't be just paint. They glanced at the clock - the shadow of the hands was now swimming like a fish, and the thirteenth dash glittered like a wet stone. The rain outside the bridge windows had picked up again. Somewhere in the far reaches of the library, pages rustled and the kettle buzzed. - 'I'll touch it,' Lena said, before thinking that this was unlikely to happen. But after all, maps like the brave and the kind. She put her finger to the blinking point. The page was cool and firm, like the skin of water. Where she touched, the ink stretched thin like a soap bubble and... it didn't burst. Instead, it began to bulge out until a small, shiny dome was formed. In the centre, something like a picture appeared - a miniature bridge, a miniature lighthouse and, between them, a real drop that refused to dry. - It's moving - whispered Olek. - Lena, look! The dome grew, bulging the map like a patch of wind. A thin stream of water ran down to the edge of the table and hovered over the floor without falling. It glided over the edge like a gravityless snail. After a moment, the stream narrowed, changed direction and, instead of a drop, a tiny paper ship slid out of the book, with a sail made from a linear notebook. It fluttered the sail, skidded down the page and splashed straight into a puddle that spilled under the table. - Do you... think it's... - Olek didn't finish, as a distant, audible clatter spread through the room. Something knocked three times. The sound came from the side of a globe standing nearby. It was large, heavy, with a brass buckle snapping the meridian. When they looked, the buckle vibrated. Once. A second. The third time - click - it sprang back on its own, as if someone had pressed a spring from inside. - Mrs Tatarak? - called out Lena, but was only answered by a quiet splashing under the boards. The globe swung open a little, so much so that something flicked inside, like lightning trapped in a glass ball. At the same time, the side of the atlas plumped further, and the shiny dome unfolded into an arch - a gate made of paper, wet as a windowsill after a downpour. On its surface, tiny fibres and writing could be seen - street names, arrows, brackets - that arranged themselves into a doorway. In the middle of it grew a handle-rod, paper-like but hard, as if glued together by drops. - This looks like a real door,' Olek stated and blew carefully. The letters trembled and the sail of the paper ship waved. - 'They're real,' said Mrs Tatarak quietly, suddenly just out of sight, as if she had risen from the mist. She had two towels in her hands and sweet-smelling steam. Her eyes sparkled, but there was something stern in her voice. - Not every map leads to a street directory. Some lead to a door. And doors... well, doors like it when someone knocks from both sides at once. - Are we allowed to look in there? - asked Olek, who, although brave, was also painfully polite. - There are three rules," replied Mrs Tatarak, putting away the towels. - First: don't leave eraser marks behind. Second: if you meet a question on the path, answer with another question. Third: return before the trail of your shoes dries. - She smiled, but her smile was as thin as a sheet of paper. - And now I have to keep an eye on the kettle, because it likes to take offence when you don't let it boil. She left them with an atlas, a globe that moved barely perceptibly, and a puddle that was transforming into a glistening lake the size of a plate. The paper ship came full circle and lazily sailed up to Lena's shoe, poking at it like a dog demanding to go out. A long, silver shadow drifted down from the clock above the shelf and wrapped itself around the gate. - 'I... I can go first,' Olek suggested, but Lena shook her head. - 'If someone calls my name, I guess I'm the one who should answer,' she replied just as quietly, although even she wasn't quite sure if she had heard the name for real or just made it up because she really wanted to hear it. Lena's hand hovered over the paper handle, and the other squeezed the Cup of Chamomile so tightly that the tea whispered in her fingers. Her heart thudded in her chest like an umbrella against the railing. Olek stood right next to her, ready to catch her if anything started to falter. The water in the puddle by the table moved and in its surface, apart from the lantern and the moon, were reflected two children's faces, a globe and a sign above the shelf: "Guides to places that aren't there yet". - Listen," whispered Olek. - Do you hear? From behind the paper door, this time more clearly, came a short, soft knock. One. Two. Three. Then silence, after which a single word hung in the air, as if someone had arranged it with steam over tea: - Lena... The handle-door flashed, the brass clasp of the globe flashed like an eye, and the puddled lake under the table twitched, getting deeper for a moment, as if someone on that side had taken a step. Lena took a breath, raised her hand and touched the cool paper with her fingers, when suddenly right next to her ear