Before he reached the ruined abutment on the canal bank he came to a scattering of loose stones. He gathered together a dozen or so cobbles and peered up resentfully at one of the more substantial buildings. Its flat windows, like dead eyes, seemed to mock him. He hefted a cobble, took aim, and hurled it. His first shot clattered uselessly against polished stone. But his second shot took out a window that smashed with a sparkling noise. The sound excited him, and he hurled more stones. But the noise stopped every time he quit throwing, reminding him firmly he was alone.

Dispirited, he dumped the last of his cobbles and turned back to the canal. On its bank, he sat with his feet dangling over blue running water, water that ran endlessly from the world’s cold side to the warm.

Symat was very thirsty.

The canal bank was a wall of stone that sloped smoothly down to the water. It would be easy to slide down there, all the way into the water. He could drink his fill, and wash off the dust of Mars. But how would he get out? Glancing down the river he saw the ruins of that bridge. The bank beneath the abutment was broken up; surely he could find handholds.

Without water he was going to have to turn back. It was a defining moment in his odyssey.

Without letting himself think about it he pulled off his boots, pants and jacket, and slid down the smooth sloping wall. The water was so cold it shocked him, and it was deep; he couldn’t feel the bottom. When he came bobbing back up he was faintly alarmed that he had already been washed some way towards the stump of the bridge. The current must be stronger than it looked.

With a couple of strokes he reached the canal wall. It was smooth, but by pushing his hands against it he was able to resist the current. Feeling safer, he ducked his head and scrubbed his hair clean of dust, and took long deep draughts of the water. It was chill, for it was meltwater from Nightside, and slightly sparkling; Mars’s water was rich in carbon dioxide.

Refreshed, he felt his energy return. There were more cities strung out along the canal like pearls on a necklace. He could hide out for days, and how that would make his parents worry.

But he was starting to feel cold, deep inside. Time to get out. He pushed off from the wall and let himself drift downstream. When he reached the ruined abutment he grabbed at projecting stones. But they were all slick with some green slime, and slid maliciously out of his hands. Scared now, he shoved himself at the protruding stones. He managed to halt his slide down the river, but only by clinging on with all his limbs, like a spider, and the water still plucked at his legs and torso.