Fourteen-year-old Lena came to the White Marsh Reserve for a holiday this summer. Aunt Hania ran a research station here and knew every platform. Lena helped to mark tracks, change the batteries in the photobuckets and take notes on the weather. She liked dusk best, when the mist rose from the reeds like steam from a kettle. That's when Rusty, a half-wild fox with a radio transmitter on, would appear. He once stole her glove, but gave it back a week later, pressed into the binoculars box. That evening the station was almost empty and her aunt had gone into town. Lena sat by the radio, which caught the signals of the cranes' collars at night. Instead of the usual single beep, she heard a triple rhythm, like a short alphabet. Beep-beep, pause, beep-beep, pause. An alien frequency flashed on the receiver screen, unattributed to any number. Rusty slid his muzzle out of the shadows and nervously flicked his ears a few times. In the distance, above the reeds, a strangely narrow blue glow suddenly flashed. Lena put on her head torch, picked up the map and towed her rucksack behind her. She didn't want to wait alone until her aunt returned, and curiosity was already gnawing. She stepped onto the wooden platform, which sang with knots and nails in the night. The signal grew louder, as if someone was breathing in an anaerobic rhythm. The toads suddenly quietened and there was a flutter of wings that she could not recognise. The beaver thumped its tail against the water, as if warning of something alien. - 'Don't get into trouble, Rudy,' she whispered, though she was the one leading the way. The fox ran right past, soft as a shadow, and sniffed the air every now and then. On the sand by the pier, Lena noticed dog tracks, but too big for a dog. Next to it lay a few crane feathers, damp and covered in fine, sooty dust. The path led towards a pond called the Dead Eye, which never froze. A signal jumped between the reeds, as if someone was flipping it from hand to hand. The reeds parted at the last turn, and the air smelled of ozone. She saw a tiny diode flashing on a black box suspended above the water. Below her, something moved hard and whined quietly, like a wet engine. Rusty ran down the ridge and stood between Lena and the box, ready to jump. Lena raised the torch higher, and the beam hit the shiny glass eye. Someone, or something, swung back the reeds and took the first step onto the platform.