Konrad's watchmaker's workshop smelled of brass, gear oil and old stories that had stopped between the gears. Clocks with uneven eyes piled up on the shelves, bobbing their heads over the springs, and in the corner, under the window overlooking the river, stood a large workbench with black rosin stains. Lena slid her fingers under a drawer and lifted it gently. "Do you hear that? This tick-tock is different," she muttered, pressing her ear to the body of the infinite perpetual clock. She was eleven years old and collected sounds: whistles, clatters, laughter. She liked to catch them like skylights. Maks, a year older, carefully pulled the cogs on the blotter. "Because it's a clock that Grandpa compiled himself. He said it goes like the wind during the day and like a river at night." He looked at his sister with a glint in his eye. "Shall we try to find the hidden stash?" "And Aunt Basia?" Lena glanced towards the door. In the back, she could hear the conversation from the museum room, where her aunt was giving the primary school children a tour of the 'Clocks of our area' exhibition. Grandpa's workshop was now part of the city museum, but they felt at home here. Maks shrugged his shoulders. "We still have ten minutes before the tour comes back for the backpacks. Quick." He instructed his sister to hold the torch. Under the drawer was a thin board with dots, like a constellation drawn with a pencil. "Those aren't random dots. It's a Cart." Lena touched one of the dots. The board clicked quietly and the whole front of the table slid out a centimetre. Maks slid his fingers into the gap and lifted the heavy top. Inside lay a cloth map, wrapped around something hard. Lena took out the package, her heart beating faster. "Whatever this is, it looks old," she whispered. Inside was a key made of brass, cool and heavy, as if it weighed not just metal but something more. The head was engraved with tiny stars and spirals. On the shank shone the letters: the RIVERS OF TIME. - "The shores of time?" - repeated Maks, savouring the words. - Grandpa was playing with poetry again. Lena unfolded the map. It wasn't a city plan, although she noticed the outline of the river and the rectangular town hall square. Instead of streets, lines ran like in a sundial, and in place of the tower a circle with twelve points and tiny stars was drawn. Next to it was taped a piece of paper with her grandfather's handwriting - hard, even, with slight swirls at the 'k'. "When three sounds at once in the city sound, And the river wind blows the dust from the leaves of the clues, Slide the key into the heart of the wheel - don't be late, And look under the light. Time itself will choose where to flow, And you - whether you want it to." Lena felt it getting warm behind her ears. Grandfather had always talked about time as if it were a river that you could listen to if you closed your eyes. Then he went on a long trip abroad to some masters' workshop, and he handed the workshop over to the museum along with a hundred stories that seemed to be trapped in screws and oils. "He... he it to us?" she asked quietly. "And to whom else?" Maks carefully picked up the key. "You know what three sounds can sound at once? The town hall bell, the train whistle and the ferry siren. Always at the full hour when the ferry starts and the goods train passes the bridge." "It's at six o'clock today," Lena whispered. "That's always when they rehearse the choir by the river and I can hear their sounds mingling with the city." The clock above the door showed 5:42pm. The door swung open and Aunt Basia slipped in with a mug of tea. "What's that whispering? Be careful not to dirty the display maps. And this... oh dear." She squinted at the sight of the key, but her face lit up with mild curiosity, not severity. "This key... Konrad really liked to hide things. He always said that whoever could listen would find everything at the right time." "Auntie, can we go to the tower?" snapped out Lena. "Just for a little while. We'll check the mechanism before closing. We promise not to touch anything... much." Aunt Basia looked at her watch. "You have fifteen minutes. The six o'clock bell? You'd better hurry up. And watch out for the stairs - they're steep. The key ... um, looks like it's from the town hall, but I don't recall one in the inventory." She turned to the door, then added in a half-hearted voice: "Konrad always said: 'Don't open it if you don't know what you'll close behind you.' But he knew you better than I did. Go." The tower of the town hall rose above the square like a tall cupboard in which someone had hidden hundreds of years. The staircase was narrow, stone, with smoothed steps and a handrail that remembered the hands of long-forgotten guards. Lena climbed quickly, hearing the echoes of her own footsteps and the clockwork machinery beneath her feet - the hard, majestic thumps of the wheels and the quiet sighs of the springs. At the top level they met the tower's keeper, Mr Iwanski, who was adjusting something at the pendulum. "Ah, Basine kids," he muttered with a smile. "Have you come to listen to the bell? Please, just don't put your fingers between the wheels. This gentleman here," he tapped the steel drum, "doesn't like to be disturbed." When Mr Iwański went downstairs to set the bell mechanism, Lena and Maks were left alone in the semi-darkness. The dial of the clock glowed with a whitish light. Up close, it was like a thin skin through which the afternoon leaked. In its centre, where the axes of the hands passed through, shone a circular ring with tiny notches, almost like teeth on the inside. It was there that the engraving of the map told us to "insert the key into the heart of the wheel". "It must be here," Maks whispered, touching the ring. He found a tiny crack in it. "See, the stars on the head of the key match these outlines." "Not yet!" Lena squeezed his hand. "The poem said three sounds at once. We have to wait." They waited, listening to the city gather its breath. The river rustled, the wind pushed the smell of apples from the market and wet stone through the gap. The clock mechanism breathed with an even rhythm. The minute hand moved to XII with a quiet swish. The tower bell struck first - a powerful, soft tone that brought everything around it to a standstill for a moment. At the same time, as if someone had whistled very far away, the high, metallic sound of a train crossing the bridge reached their ears. And immediately afterwards, almost overlapping the first, came the low, hoarse whine of the ferry's siren as it pushed away from the shore. Three sounds at once. Lena felt something mark in her chest. Maks nodded, as if he was just waiting for it. "Now." As they slid the key into the slot, they felt a slight resistance, as if the mechanism was considering for a moment whether to trust them. As it went in, the whole thing trembled like a violin with someone pulling the string with a bow. The ring in the centre of the dial flashed with a cool, silver light. The hands - hour and minute hands - trembled and stopped moving forward for a moment. "Turn," whispered Lena. Maks turned the key one tooth. Something clicked. At the bottom of the dial, between the numbers V and VI, appeared a thin arc, carefully cut into the enamel, which no one below would ever see. A metal mark began to extend from the arch, like a seal - an engraved mark resembling a wave with an arrow through it. The air became thicker and the smell of brass mingled with something cool, sharp, like the morning just before dawn. "Can you smell it?" Lena muscled the shield with her hand. A tingling sensation ran under her skin. The light behind the glass thickened, as if from outside it was not a street but a milky lake. Tiny droplets appeared on the opening, and, surprisingly, they were not water droplets at all. They were like skylights stuck to the glass. "Another half turn?" asked Maks, his voice quieter and more serious than usual. "If he chooses for us, it's now," replied Lena, repeating the phrase from the rhyme and suddenly understanding that Grandpa could have foreseen this moment. What if there really is something waiting here? What if there is something on the other side? She didn't finish the thought as the dial brightened so that they both closed their eyes. After a moment, the light dimmed and they saw something that made them forget to breathe. On the other side of the glass the outline emerged - not of their market, not of the aerial roofs or the pigeons. They saw a narrow street paved with large, uneven stones. Instead of cars, there were carts, and the people walking past the shield - yes, they could see them as clearly as if they were looking through a window - wore long-breasted coats and hats different from their usual ones. Someone was just carrying a stack of candles instead of lamps. In the background, where the river should have been, there was a mist the colour of morning milk. "It... can't be now," muttered Maks. Then, very clearly, they heard a voice, as if coming from under the water, yet clear and familiar. "Leno. Maks." They froze. Lena felt the fingers of the key suddenly heat up and the hairs on the back of her neck stand up. "Did you hear that?" she hissed. "I heard." Maks tightened his hands on the head of the brass key. "That... sounded like..." "Like grandpa," Lena finished soundlessly. At the same moment, someone's hand reflected from within on the milky glass, right next to their faces. It wasn't transparent or scary - just an ordinary gloved hand, made of thin material, like an old portrait. On the other side, someone stood so close that the shadows of his eyelashes trembled in the light. "If you can hear me," the voice again, more emphatic, "you only have a moment. The indicators will not wait. The key is yours, but so is the choice. Turn it. Or go back and shut everything down forever." Inside the mechanism, something clattered, as if a free weight had clattered against the brake. From below came the distant laughter of someone in the market, and then silence again. Lena looked at her brother. Maks looked at Lena. Time hung on the edge, like a drop about to fall. "On the count of three?" whispered Maks, and the glass on the other side shimmered like the surface of a river as the shadow of a cloud passes over it.