On Friday evening, the last before the summer holidays, the roofs of Birchwood looked like scales of dark glass. Heavy clouds hung over the town, and in the market square only a few tourists were taking photos of lanterns that still remembered two wars. The clock tower, made of brick darker than a wet cube, hummed quietly from the wind, as if it were breathing itself. This was the best time to go inside - the archive lady had long since closed the door and the guard liked to take long coffee breaks. I was fourteen and had a key on a string that pressed into my collarbone as I ran. My name is Lena, and my heart beats fast, although I always pretend to be calm. Oskar, my neighbour from third, was running behind me with a rucksack full of tools that his grandfather called "something that will definitely come in handy one day". Oskar had fifteen, an eye for detail and a talent for upsetting people when he was scared. - Is this really a good idea? - he wheezed as we stood under the metal door from the back room. - 'If we bang something, they'll call us vandals. - 'We're not going to smash anything,' I replied, pushing the key into the heavy lock, 'just find the answer. Great-grandfather Jan Kłosek was a watchmaker and disappeared on August thirty-nine, leaving behind his workshop, a box of letters and family silence. In the moments when Grandma would forget, she would say that "he was fixing something, something bigger than a watch". He also left behind a brass casket that I found a fortnight ago in the community archive, moments before Mrs Aniela told me to return it for cataloguing. I have never been so grateful that volunteering can drag on after hours. The stairs in the tower were narrow and winding. Moisture from the rain pressed into the stone, and each step sounded like it was reverberating down a hundred small corridors. It smelled of dust, machine oil and pigeon feathers. Through narrow windows we could see the Birchwood roofs - red as cracked bricks. When we reached the level with the mechanism, we heard a steady, slightly snarling sound: 'tick... tick... tick...', as if the building's heart had not yet decided whether it wanted to beat. The room, which was called the workshop, was full of the sort of things that one only learns about in an ordinary technology room from illustrations. On the walls hung wooden drawers with metal knobs, in them - slides, springs, leather straps, needles and something that looked like miniature cheese knives, which it most certainly was not. On the table lay my target: the casket I had crammed into my rucksack before Mrs Aniela had time to describe it. Now it lay here because I needed to see what was inside when no one was looking anymore. - Do you still think it's just a box? - I asked, taking the lid off. Oskar leaned over. Inside lay a brass disc the size of a hand, heavy and cool, the inside as openworked as a spider's web. On the rim was an engraving: "What was, will be". Under the disc, a letter in neat handwriting, with a coffee stain and a few words smudged as if by rain. "If you put the Heart of the Clock in place, remember: it beats as you do. Don't set the nine if you are alone. If you are two - don't panic. Time doesn't like shouting." - Heart of the Clock? - Oskar snarled. - Dramatically. - But his fingers, usually sure, were now touching the disc carefully, as if he might burn. The mechanism of the tower clock looked like a giant version of all those little things. The gears interlocked and pushed back, the shafts rotated slowly, panting with oil. There was just something missing from the spot that fitted our disc - as if someone had taken the heart out of the cage and left an empty socket. - Did he take it out? - Oskar asked quietly. - Your great-grandfather? - 'Or he arranged it so that someone who would know what to do with it would find it,' I replied, before I had time to think that, after all, this sounded far too serious for someone with a bar and a pen with a unicorn in his backpack. I slid the puck into place. It clicked. Something in the whole structure breathed. The 'tick' sound became even, cleaner, like a new piano in a school music room when someone finally tunes it. I felt a current go through me from my fingertips to my shoulders - not pain, just an awareness of something changing the rhythm around me. Oskar also twitched. - Can you hear it? - he whispered. I could hear it. The ticking synchronised with my pulse. For a moment I felt as if I were standing up to my ankles in a river that was flowing exactly as I was breathing. The minute hand on the huge dial above us twitched, made a slight half-turn and stepped back, as if frowning. Behind the milky glass of the dial, the light was translucent, as if it were making a window. For a second I saw a square different from ours - no billboards, a ladder cart, a horse with the rest of its mane whitening from the rain. I blinked and the image disappeared, leaving only my own reflection and drops of water gliding on the outside of the glass. - Is this a trick? - Oskar tried to sound reasonable. - Like holograms from science fiction? Instead of answering, I picked up the letter. Inside were two more pieces of paper. One contained a sketch of a mechanism with something described as a 'knot of hours' marked on it, the other a few sentences that sounded as if someone had written them in a hurry: "It's not about leaps, like in books. It's about tensions. Nine with nine is the gate. No more than nine beats. Don't open if you hear footsteps other than your own. They will smell of smoke and milk." We looked at each other. - Milk? - Oskar croaked. - Really? At that moment the air grew cooler. Somewhere below us, in a stair recess, the steps creaked. Not the way they creak when you run - more like the footsteps of someone who knows the building inside out and doesn't have to look underfoot. A sweet smell came to the nose - not fresh, more like the kind that has stood on the cooker in an enamel pot for too long. And something else - a pungent note of smoke, not cigarette smoke, but burning coal. - Is that the guard? - Oskar whispered again. I shook my head. The guard smoked menthols and was unlikely to bring milk. Instead, the bell chains rang in the lower corridor, as if someone had touched them out of curiosity. Something tightened in the mechanism, knocked, the wheels went round their teeth a fraction faster, and my heart sped up so that I could almost hear it in my temples. - 'Don't set the nine if you're alone,' I repeated aloud, as if that would help. - 'But we're two,' Oskar pointed out and even smiled. - It's just that... - It's just that we don't know what we're going to do if something starts - I finished for him. I moved back to the big cogwheel that moved the hands. By its side was a crank, heavy and cold, and by the crank was a brass plate with the hours engraved on it and a modest arrow to clutch to the mechanism. His fingers found the right indentation by themselves. Oskar stood close, as if he could catch something if it fell out. His breathing was shallow. - 'If something goes wrong, we shut everything down and run away,' he said. - We won't be heroes. We don't need to be. - 'Okay,' I nodded, though I knew that if great-grandfather had left it for me, I couldn't just lock up and go downstairs as if I'd never been here. I touched the arrow. The mechanism responded with a slight resistance, like a muscle that doesn't yet know whether it should tighten. The hour hand moved with a barely visible click. The dial became brighter. From behind the glass I saw the square again - this time with a girl with her hair tied up in a kerchief, carrying a bucket. She moved through the image as quickly as if someone had rewound a film. Then the disc was streaked with the usual rain. - 'Up to nine,' said Oskar, as if trying to convince himself. - Up to nine strokes. And the end. I spun slowly. The ticking sound changed once more, as if waiting for the right tone. The moment the arrow passed the eight, something in the floor trembled, as if a tram had passed beneath us, although, after all, there were none in Brzeziny. The bell chains tightened like a chord. I could clearly hear my own pulse, focused, hard. The strange footsteps from below sounded again, closer this time. Closer than our actual stairs would allow. We raised our heads at once. A streak of light appeared on the milky glass of the dial, thin as a crack. It glided downwards, leaving a sparkling trail behind it. Inside the workshop, the air now smelled of ozone, as if after a violent storm. I pressed the arrow one more tooth. Nine. The bell above us rang out with a bass that filled my ribs and pushed the air through my hair. Once. Dust sprinkled from the chains like coarse flour. Two. A crack widened in the dial and an image spilled out behind it: a marketplace in the sun, a man in a hat, a girl in a mid-calf dress lifting a bird feather. Three. Footsteps stopped just outside the workshop door, though no one opened it. Four. I heard something that sounded like voices, but distant, as if through water. Five. Oskar squeezed my wrist - not hard, just enough to feel that we were next to each other. Six. The second hand on the dial sped up and then slowed down, as if it was dragging its feet on a decision. Seven. Then the face of a boy about our age appeared in the scratch. It wasn't sharply defined - more like an old film - but when he moved his lips, I understood what he was saying. He had the same eyes as the great-grandfather in the only portrait in the living room. "Now." Eight. The tower groaned, not like a building, but like an animal. The light on the dial became unnaturally white, like on a frosty sunny day. The shadows in the workshop arranged themselves in lines running from the edge of the table to my shoes. It smelled of milk and smoke so intensely that it made my head spin. Nine. At the same instant, the arrow I had been holding on to snapped out from under my fingers, as if the mechanism had decided that it was now leading the way. The Clock's heart thumped so hard that I felt it all the way through my teeth. The floor bent, but not as from a weight - more like a wave. Everything around me - the drawers, the tools, the dust - vibrated and blurred for a moment into bands of colour. The clock face was no longer milky glass; it was a gate, shimmering like the surface of a sunlit river. The door behind which the footsteps stood moved a millimetre, then another. Someone on the other side touched the handle from the inside - the same one I had turned earlier, entering. The lock squeaked. Oskar drew in air violently. The boy in the dial raised his hand as if to say hello. The seconds hand melted into a bright streak. Before I had time to say anything, the light leapt from the dial like a string, cut the workshop in half, and under my feet the boards suddenly....