After the storm, the townhouse on Maple Street smelled of wet dust and freshly sawn railings. The lift groaned at each floor like an old double bass, until one afternoon it stopped where no door had ever been before - on the mezzanine between the third and fourth floors. Lena was the first to poke her head out of the cabin. She was eleven years old, freckles scattered like constellations and a green notebook with a sticker "Imagination Notebook", into which she wrote down everything that didn't fit into an ordinary day. Olek, a year younger and with pockets full of springs, rubber bands, miniature screws and buttons, stood next to her. He claimed to be able to catch echoes in a jar and store them for worse weather. - 'This mezzanine wasn't there in the morning,' Lena whispered, peering down a narrow corridor whose walls were still glistening from the rain, though they had no window. - 'Maybe the lift was wrong,' replied Olek, but it sounded as if he was explaining it more to himself than to her. The corridor ended in a blue door. It was narrow, smooth, with a brass handle that bore the marks of many hands. Above the handle, instead of the usual number, someone had painted neatly: 13½. Below, in chalk, was written cursorily: "Enter only with imagination". Next to it was a tiny Judas, and from behind it came a barely perceptible noise, as if someone on the other side was turning the pages of a very, very thick book. - 'This is some kind of joke,' muttered Olek, but he was already stretching out his hand to knock. Lena stopped him with her finger. - Listen. They put their ears to the wood. The noise changed to a rhythmic, quiet tapping. Not like footsteps. More like... a pen tapping on the tabletop? - 'It sounds like someone is writing inside,' said Lena. - If it's a joke, it's a very elaborate one. Olek slipped his hands into his pockets and pulled out his favourite jar, the one with the blue cap. - Just in case. If something calls out to us, I'll tape it inside. - We'll scoop it up,' Lena corrected him with a smile. - And I'll take the notebook. They ran downstairs to get the equipment, and when they returned, the corridor seemed to lengthen. The light on the ceiling twinkled, casting patterns on the walls that resembled the shadow of birds' wings. Olek looked around uncertainly. - I swear, it was shorter. - 'Or our steps are longer today,' Lena answered him and looked at the door handle. It was warm, as if the door had been exposed to the sun. - Ready? - Ready. - Olek pushed the jar under his arm. In his other hand he squeezed a torch with coloured film on the glass. - If anything, I shine it blue. Blue is said to be calming. Lena nodded and gently pressed the handle. The door gave way without a creak, as if it had been waiting for just that touch. Beyond the threshold was... air. Air that smelled of heated paper, ink and the leather of old covers, but also something citrusy, like summer lemonade. The light had no single source - it shimmered softly on the edges of objects they couldn't name at first. The floor was made up of wide, cream-coloured strips resembling sheets of paper without lines, yielding underfoot like hard mattresses. From the ceiling, high and expansive as the sky, dangled light islands made up of notes, sticky notes and bookmarks that fluttered when a breeze moved. The strangest thing, however, were the butterflies. They flew in front of their faces almost silently, with letters dancing on their wings instead of patterns. When they sat down, the letters arranged themselves into unfamiliar words and immediately disintegrated, as if someone had not yet decided what they actually meant. - Did you see? - Olek pulled Lena by the sleeve, pointing to a distant metal truss balcony, attached to nothing so that it hung in the air. A whale was passing over it. Not of flesh and bone - of windows. Frames and curtains flashed in its side, and when it opened its mouth, a quiet 'click' could be heard, like the tilt of an old sash. - This place is... - Lena searched for a word and couldn't find one that fit. - It was as if someone had drawn out a thought and then given it to the world in four dimensions. She closed the door behind them. It did not slam shut, but closed softly, leaving a narrow gap through which the whisper of the corridor entered. On the inside of the panel, the one on the interior side, hung a typewritten inscription: "Guest, leave your shoes where the repeats end". They looked down. Indeed, after a few steps the white stripes of the floor replicated the same, and then suddenly - a change: instead of white there were lines of sea green, like a spider web on a shallower lake. - 'The shoes stay here,' Lena announced and slipped off her trainers. Olek hesitated a second, but it was warmer on the green lines, as if someone had spread the sun there. He stayed in his striped socks. Somewhere very far away, or maybe very close, something sounded, like the clinking of a spoon against a teacup. On the wall - if it was a wall - letters flashed and cobbled together into a sentence: "PREPARE: take one bold question, half a step back and three quick glances to the side." - 'That looks like an instruction manual,' Olek remarked, bringing the torch closer. - But why "sideways"? - 'Maybe because the important thing prefers not to stand in the middle,' Lena replied with seriousness and wrote down in her notebook with a yellow pencil: "An instruction that asks you to look sideways". Olek unscrewed the blue jar and - needless or not - caught some air inside. The cap vibrated slightly, as if the jar had switched to receiving. - Can you hear? - he asked suddenly. - Someone is talking. A voice, quiet as if from a neighbouring room in a dream, carried their names. At first timidly, then more clearly, as if dictated by a megaphone wrapped in a scarf: 'Lena. Olek. You had better come before the wave." - What wave? - Olek reflexively moved away towards the door, but the door... no longer stood exactly where it had just been. The closed gap had turned into a narrow shadow, and the rectangle itself seemed to have retreated a few steps, although they had not moved away from the threshold at all. - Come on," said Lena. - Three more quick glances to the side, as the instructions instructed. She looked around to the right. A staircase of cards flashed at the edge of her vision, folding and unfolding by itself, as if learning its own shapes. She looked to the left. Between the two shelves with the words "Tomorrow" and "Almost" flashed something like a path - invisible until you looked at it. She looked to the right once more and... missed a third time. From the depths of the room, from behind a balcony for nothing, something that was not water but looked like a wave was coming. Thousands of paper cranes, pages, phials and strips from the margins rose and rippled together, forming a soft ridge that cracked like feathers. At its head, a sheet-sized glyph flew like a flag with the words: "YOU ARE NINE MINUTES LATE. ANOTHER RUNE IN A MOMENT." - Rune? - Olek was surprised. - Perhaps he means a round? - Or a fleece, the kind made of sheep - snorted Lena, although she wasn't laughing at all. The wave of cranes accelerated. For a moment it formed an arc, like a gate, and something like a river flashed beneath it. Not water - a string of sentences, written live, that flowed and changed and glittered with letters. - 'If it's a river of sentences, you can probably swim on it,' whispered Olek, tightening his fingers on the jar. - But first... - 'First the question,' Lena finished, remembering 'one bold one'. She could feel her thoughts lining up, each one of them impatient, each one wanting to be the one most needed. - Who is someone who invents places for imaginary things? The voice, the one from under the deep quilt, spoke again, closer this time: - Good question. The answer will be known by the footsteps. From the shelves of 'Tomorrow' and 'Almost', two volumes fell to the floor, opening evenly in the middle. The pages shimmered like mirrors in the sunlight, and the chill and smell of the forest after the rain came out. "Footsteps," Lena realised. - "You have to follow the footprints." Only that the footprints were everywhere: the imprint of the notebook's edge on the tabletop, the swish of sticky tape, the luminous streaks left by the movement of butterfly wings. Olek pressed the torch. The blue light turned the dust particles suspended in the air into a constellation. The window whale curled upwards and released a cloud of vapour from its mouth, which formed into a question without a question mark - uncertain, not yet ready. - 'This leads us,' Lena stated, and moved towards the paper arch. Each step along the green lines sounded soft, as if they were treading on words just being formed. A quiet, metallic rasp came from behind them. They turned at the same time. The door 13½ was shrinking, slowly and insistently, as if someone had rolled it up. Soon all that was left of them was a blue box the size of a pencil case, which had been sucked deep into the wall by some invisible string. - 'We're going back somehow, too,' said Lena dryly. Not like a question, more like a note to her future self. - As long as we're coming back. The paper wave was already so close that they could feel its light shadow on their faces. Butterflies with letters began to perch on their shoulders, as if to say, 'The words will come in handy'. Olek's jar shook with a quiet tremor. The cap unscrewed itself half a turn, and a murmur escaped from within, which, released, folded into a short sentence: - Not all at once. A step and a breath. - One step," Lena repeated. - And a breath. They shook hands. Above their heads, the whale whispered something that sounded like a 'click'. Beneath their feet, the lines of the floor merged to form, for a moment, a clear bridge over the river of sentences. To the left, from the 'Almost' shelf, a hand folded over the tabs and pointed to the archway. On the right, between the notes, something heavy and wide rose to move, parting the air like curtains. - Now! - shouted Olek and lifted the jar as if it were a compass. A wave of paper birds swooped towards them, spreading their wings so wide that for a split second the world shrank to a white noise and a flicker of letters. Lena tightened her fingers on her pencil, ready to write down the first thing she saw on the other side of the arch, when suddenly a figure emerged from behind the balcony on nothing - as tall as a bookcase, with a head made up of maps and arms woven from lines - and with one step stood exactly in front of them, shadowing the bridge....