Alastair Reynolds: An exclusive short story for New Scientist

It was a foggy December, colder than usual.

An old woman waded through the shallows of a concrete-bound river. She wore overalls and a breather mask, a meshwork hopper slung over her back. She leaned hard on two sticks, one with a grabber on the end, the other a net. At intervals, she scooped some grey, slimy clump from the river and deposited it in the hopper.

Dusk was falling as the woman paused for breath. She rested on the sticks and took off her mask. She gazed at the fog-shrouded stratoscrapers rising either side of the river, searching their…