The first time I heard this sound was in the darkroom, although after all, nothing there should sound like metal. The fan hummed habitually, the water in the cuvette rippled quietly, and the shape of the footbridge on our rusty viaduct over the Birch Mountains slowly emerged from the paper. I was alone in the school, already in the dark. As the image took on a contrast, I saw my silhouette against the railing, with my camera raised to my eye. And another. Someone standing further away, on the edge of the tracks, turned sideways to me, bleached as if cut out of the mist. I didn't remember anyone being with me at the time. I folded the paper into a roll, tucking it into the tube, and I knew I wouldn't fall asleep unless I went back to the viaduct again, this time with someone who could hear what I remembered only as a cool tremor in the air. Oskar smiled crookedly when I told him. "It could be a double exposure. Or someone walked into your frame and you didn't notice." He nodded immediately, however. "I'll go." Nina had an expression on her face that I couldn't pierce with argument; she didn't doubt, she just wanted to check. "I'll get the recorder. If it's sound, we'll catch it." We left after ten o'clock. The city was already muffled in the yellow light of the windows; the River Spark carried the smell of wet leaves and iron. The viaduct loomed over the concrete basin of the former station, its metal arches as dark as the back of a huge fish, and rare drops glinted in the railings. The tracks no longer led anywhere - the line had been closed for years. To the south the tunnel was buried, to the north it was walled off with a thick wall on which someone had long ago painted a slogan, a half-started protest from two terms ago. Even so, people said that in the winter, when the air is thin, a sound comes through the bridge at night, as if the metal wanted to remember working. Climbing the viaduct was not difficult, although the fence made a menacing face. A loose mesh dangled between the rungs and we slipped through it cautiously, feeling the chill begin to press in under our jackets. No heroics were needed - just caution not to snag the backpack on the wire. At the top, the air was different. Quieter. The tarmac, rutted from years of wear and tear, cracked in cracks from which hard grass grew. The balustrade, cold and sticky with moisture. In the distance, the lamps by the river formed a line of luminous beads. I set my rucksack down beside a concrete pillar, pulled out my tripod and set it up where I remembered the chalk line I had marked for myself before. My fingers were stiff as I screwed on the adapter, but it was a feeling that always tidied me up. The camera - my old Nikon, inherited from my grandfather - surprised in the footwell like blocks that have fit together for thirty years. Oskar set the thermos on the ground. "I'm going to make tea. Someone tell me one day that the shiver can be outsmarted, I'll show them a cup of ginger." Nina put the recorder on the railing and fired up the red dot. "I'll also turn on the low cut. The wind likes to trick your ears." Something twitched inside me. I didn't know she liked it - but I believed her without a second thought. - Tell me again where the person was standing," she asked. - Exactly. I walked up a few steps, placing my hand on the cold steel. - Here. More or less here. It's just that... - I hesitated. - In the picture, the light was like from another hour. As if the shadow appeared not where it should be. Oskar looked down into the black rectangle of the former platform. - 'How about one of those jumping bellows people? - he threw in a joke, but it hung strangely in the air. I didn't answer. I didn't believe in coincidences when my camera came into play. When it got really quiet, the last sigh of the night line bus came from the distance. Then just drops dripping from somewhere under the arch, and the wind moving across the metal verglas, as if someone was dragging a finger along the rim of a glass. I set the time for thirty seconds. I liked long exposures - things come out of them that the naked eye can't see. I snapped the trigger on the cable and heard a quiet 'click' that echoed like a yellow reflection in a puddle. - 'Do you have a torch? - Nina asked. - Don't shine it into the lens, but if anything.... I nodded. The torch was in my jacket pocket, next to my phone. Everything was banal: three high school students on an old bridge, a little chill, a breath. And yet, in this banal arrangement, every sound was like a sign I couldn't read. We felt it for the first time with our feet. Not with the ear, but with the skin. A barely perceptible tingling sensation that made its way through the concrete to our trainers. Instinctively I looked at the tracks. The leaves that had accumulated between the sleepers trembled. A metal cable, abandoned nearby, moved like a blade of grass. Oskar glanced at me and raised an eyebrow. "After all, nothing rides here". - we said confidently in our heads simultaneously. Nina's recorder blinked softly, as if something had caught her ear. - 'It's not the wind,' she said, without taking her eyes off the indicator. - It's... even. Instinctively I looked at the semaphore, the old one that should have been dead for years. It stood black, hammered into the ground like a javelin. I swiped my torch, but before I could click, a red spot lit up on top of it. At first faint, pathetic, as if a flat battery from a remote control had been plugged in to power it. Then it lit up more fully, sultry and full, like a plum in a jar. I took a step back and felt the bail of the camera press into me, reminding me why I was here. - 'Semaphores don't light themselves,' said Oskar, calmly, like someone who doesn't want to betray his own throat with sound. Nina answered nothing, but her hand slipped under my jacket, reached into her pocket and pulled out a torch. She clicked it on. A cone of light cut through the chill and lay on the wall of the walled tunnel. Water glistened on the bricks. What we saw immediately afterwards was not actually a sight - more a breath of light. First, a pale oval appeared in the depths of the darkness, as if someone had reached out a finger there and touched the darkness from within. Then the oval narrowed and lengthened, frowned, taking on the shape of... a lamp? Except that no whirring could be heard, no heavy breathing of steel wheels. Oskar approached the box by the railing, the one marked 'Emergency Phone'. I always thought it was dead, deaf like the rest. This evening it had a green LED that blazed like a test. Oskar put his hand on the handle, hesitated and lifted the handset a centimetre. For a fraction of a second we heard something that resembled the sound of the sea applied to the ear. Not so much a hum as a sort of distant, even tremor. Oskar immediately hung up the phone and the diode went off, leaving us again in damp blackness. I took another picture. A long time. My heart thudded like a metronome - not too fast, but relentless. In the viewfinder, the light in the tunnel was no longer a pale oval. In the viewfinder it was closer. Much closer than I could see it with the naked eye, as if the cameras and eyes were measuring two different worlds. To the left, by the pillar, a shape outlined itself. A silhouette, like the one in the print, out of focus, wearing a coat or a hooded jacket, it was hard to tell. I couldn't see anything like that in reality. Only in the black rectangle in front of my eye was someone standing and doing something with his hands, as if tying his shoelaces. - Oskar... - I whispered, without taking my eye off the viewfinder. - There is someone on camera. On the left. By the post. Oskar did not approach abruptly. He approached the way one approaches a chained dog. - Don't move - he said very quietly. - Not now. Nina slid her hand under my elbow, propping me up slightly, as if the camera might be heavier than it is. The recorder on the railing blinked spasmodically, caught a sudden drag, as if something had run its fingernail over a steel cable. The semaphore changed colour. It jumped from red to a determined green light, unaccustomed to being here. The air thickened, my breathing became shallow, and I felt that peculiar taste in my throat: metallic, electric, like when you touch a battery with your tongue. In the viewfinder, a silhouette raised its head. I had the impression that it was looking straight at me - although I couldn't see a face, only a shadow. The light from the tunnel was either already a step away or the camera was lying to me. I let the air out very slowly, as if I could thus outwit the silence. Suddenly I felt a light tingle on my right shoulder, clear as the touch of fingers passing through the fabric of my jacket. Not some "I thought". A touch. Here and now. - 'Maya,' said someone just behind me, so close that for a split second it even drowned out the even murmur in the tracks.