In the bay after each storm, the land smelled like a freshly opened book: salt, wet wood and rain-smudged print. That afternoon, the wind was still sorting out the remnants of the clouds over the bay, and the seagulls were screaming as if they had something urgent to say to someone. Nina stood at the end of the pier, sliding her hands deeper into the sleeves of her sweatshirt. She was fourteen, with a notebook full of handwritten sketches and a habit of listening to silence as intently as music. - 'You're late,' said Kacper, emerging from behind an overturned bench. He was fifteen, his knees perpetually scratched and his pockets stuffed with things that 'might come in handy': a yellow torch, a string, a penknife and a phone on which he could run weirder programmes than all the adults within a dozen kilometres. - 'The train was wandering around all the stations,' Nina replied. - Do you have a sketch? Kacper pulled a roll of paper tied with a blue ribbon from his bag. They unrolled it carefully on the board, holding the corners with pebbles. The sketch had been drawn years ago by his grandmother Helena, when she still lived in the lighthouse on the headland. It was no ordinary plan of the pier: next to the beams and pillars in the water there were symbols resembling small waves, arrows marked with the words 'north wind' and 'breathless sea', and where the pier ended in a darker board, there was a circle with thin lines instead of numbers. - 'The clock,' whispered Nina. - 'It's really here. The circle stuck inside the pier so cleverly that it was easy to miss. The brass bezel was fringed with a green patina, and the places where the numerals should have been were decorated with bas-reliefs: a fish with its eye open, a drop, a seagull's feather, a wood jar, a shell, a cloud, a thunderbolt and a hand shadow. Two pointers, thin as ribs, ended in petal-shaped arrowheads. One stood by the pen mark. The other trembled slightly, although there were no mechanisms or springs nearby. - 'A tidal clock,' muttered Kacper, crouching down. - It reads the movement of water by resonance. 'Or it's just a nice looking thing and Grandma added a legend because she liked to involve the kids in her stories. Nina smiled briefly. Grandma Helena collected sounds the way others collect stamps. Her sketches smelled of ink and the sea. She never lied; she just let the world do the things it was always capable of doing. - "When the north wind dies down and the waves give up the sand, set the marks for four dawns," Nina read from the margin of a sketch. - That's today. The storm has calmed, and see: the water is going away. Indeed, the water level was diminishing like an inhalation that someone is slowly retracting into their lungs. Between the beams of the pier, bundles of seaweed and black, edged stones were revealed. Strings of lights, strung over the planks, still dripped with rain, although the sky was already clearing. Somewhere far away a dog barked, and then everything was covered again by that special silence that Nina had always sought - a silence in which every step sounds clearer. - 'Set the signs for four dawns,' repeated Kacper. - Four dawns, that is...? North, east, south, west? Or maybe four moments when it gets brighter? Or is it some sailors' jargon. Nina reached for the pointer. It was as cool as the skin of the water in October. When she carefully moved it, the metal beeped faintly but moved smoothly, as if waiting for someone's hand. Kacper set his phone on the sound generator app. - 'If it resonates, let's try it with A first,' he muttered. - We'll see if he likes the classics. The 'A' sound spilled over the pier like a thin thread. At the same instant, tiny ripples ran across the surface of the brass, like on a puddle when the first drop falls. The pointer twitched and jumped one mark, stopping at the relief of the drop. Nina and Kacper looked at each other. Then at the sketch. Then at the water, which had just touched one of the beams and moved away as if offended. - 'It's not just a decoration,' Kacper stated, suddenly quieter. - 'Either someone ingenious put a wave-counting mechanism in here, or...' - Either the sea responds,' finished Nina. - We are shifting to four dawns. They crouched over the circle, moving the clues according to their grandmother's note. In each position, Kacper triggered a different tone. Sometimes it was a barely audible buzz, sometimes a soft, high-pitched swish. With each movement, the metal seemed to gain depth; tiny glowing dots appeared in the slender grooves, as if someone had sprinkled plankton powder there. Nina felt the planks beneath their knees tremble minimally and the air thicken - not with anxiety, but with anticipation. As they adjusted the hands so that the long arrowheads aimed at the pen, thunder, shell and palm shadow, something happened that no one could have thought of on an ordinary Monday. Instead of a ticking, they heard a soft click, like a lock closing from the inside. The brass ring twisted a millimetre. Through the gaps in the boards, a cool light began to rise, at first barely visible, then as bright as the glow of fish beneath the surface of the water on a moonless night. - Can you hear it? - Nina asked. They heard. Something very low, like breathing under a scale. And also a murmur, like the pages of a big book sliding past each other, where each page was heavier than the previous one. - Is it dangerous? - Kacper asked, but he didn't sound frightened. He sounded like someone who had just been given a problem to solve, and the kind of problem you want for months. - 'I don't know,' Nina replied and smiled into the darkness. - 'But I feel that everything is attentive. The moment she said this, the middle section of the pier collapsed about a hand's width and spread out like wings. Beneath the planks a spiral of steps, carved from wet black stone, was revealed. Drops did not run down them as they should have, but stopped at the edges, as if holding their breath. From the depths came the same low muttering. It blew cold with the smell of rust, algae and something surprisingly sweet - like aniseed thrown into tea when your throat gets cold in the wind. Kacper switched on the torch. The beam of light was narrow, but it was enough to see that there were marks carved on the first steps similar to those on the clock. Those on the edges became brighter as the light traveled over them, as if they were responding. - Will it snap if we go down? - asked Kacper in a half-hearted voice. - 'If there's a lock, there must be a key too,' replied Nina, pointing to the brass ring. She gently touched it with her finger. The metal vibrated like a string. A cloud broke on the horizon and the last streak of sunlight aimed at the clock. The shell and pen flared for a split second, like an eye giving a sign with a blink. The seagulls suddenly fell silent. The wave surged, but instead of falling under the pier, it stopped at the line of steps, slithered as if through a pane of glass. - Shall we go? - Kacper asked, and there was an excitement in his voice that Nina knew too well not to succumb to. She slipped her rucksack off her shoulders, slipped her notebook behind her belt and squatted on the edge, feeling a pulse rising from deep within her that was cooler than anything she knew on the surface. A shadow ran across the level of her ankles, just off the first step, though the torch glowed steadily. Kacper squeezed the handle tighter, the sheaf of light twitching. - Can you hear? - she whispered. A single, clear thump came from below. As if someone had knocked on the underside of the world. Nina tightened her fingers on the railing. A second time - this time deeper, closer. The wooden planks of the pier responded with a quiet clatter, as if the old house had taken a breath. Kacper took in a breath and his torch trembled just enough to see, for a fraction of a second, something moving in the white of the light - a round surface, shiny, not quite water and not quite stone. And then came a third thump, so close that they felt it in their bones, and the brass ring behind them answered with a short, metallic whisper