Lena was seventeen years old and had been missing her grandmother for six months. In a town near the Carpathian Mountains, it was said that Halina knew the language of rivers. After the funeral, a package arrived: a herbarium, a worn brass bell and a sealed letter. Grandma wrote that the bell must be returned when the river suddenly reverses course. Then something will open up that it is better not to talk about on the phone. Lena kept the letter in the pocket of her school blouse, although she preferred not to believe it. In the afternoons, she tidied up the herbarium, noting small symbols from the margins next to each leaf. The symbols returned on the stones of the old viaduct, where the Wisłok made a tight bend. At night she heard whispers from the dark side of the bridge that knew her name. She preferred to think about her chemistry lesson rather than the water changing her mind. That May came a storm with no lightning, just a heavy, steady rumble over the hills. The river crawled over the gravel, then reversed its current like someone turning over a cassette tape. Lena texted Olek: meet by the viaduct, take a torch and chalk. Olek came in breathless, with a rucksack full of nonsense, including a rope and sandwiches. It was still light, but the wind was carrying the birds lower, as if trying to hide them. Beneath the arch of the bridge they saw signs from the herbarium, bitten into the granite like fire marks. Lena lifted the bell and struck, carefully, once, as Halina wrote in a letter. The sound did not reverberate, but entered the water, which trembled like skin. Moths flew over the current, drawing a circle, and the air became unpleasantly clear. Olek lowered his voice, asking if it was legal, but the scream of the heron drowned out the answer. On the fifth beat, the current under the bow turned abruptly, as if someone had turned a valve. The crunch of the bell caked in the palm of his hand, and the stones overhead sounded thinly. Something long and sleek, without wheels, slid out of a dark gap between the blocks. It stopped just short of the water, like a wagon, though it had no joints or windows. The door slid open quietly, and a whisper came from inside: Halina's name and her address. The air smelled of needles and smoke, though no flames flew from the wagon. The same signs as in the herbarium flashed on the floor, arranged with wet lights. The bell flared milky, as if recognising the house, and the riverbank stopped breathing. Olek whispered that it was crazy, but he was already placing his hand on the doorframe of the entrance. From the depths of the windowless carriage, someone answered with two words Lena had spent years learning. Come in, Guardian, before the fifth echo dies down, or the river will ban you from returning.