“We haven’t all got a prefect’s blood in our veins, miss,” he murmured laconically. He settled himself more comfortably, his spear cradled against his chest, and resumed his patient inspection of the board.

“Well, my backside is getting cold,” she said. She jumped to her feet and began to pace up and down along the little tiled ridge behind the battlements.

It was a bright autumn day, and the northern British sky was a deep, rich blue. This was a sentry’s lookout point, here on the wall of the fortress of Brocolitia—in fact, strictly speaking Magnus was on sentry duty right now—and she could see across the countryside, to the farthest horizon in every direction. The land here was rolling moorland, bleak even at the height of midsummer, and as autumn drew in it was bleaker still. There was no sign of life save for a single thread of black smoke that rose toward the sky, far to the north, so far away its source was lost in the mist that lingered even now, so close to noon.

And if she looked to left or right, to east and west, she could see the line of the Wall itself, striding away across a natural ridge of hard, black rock.

The Wall was a curtain of tiled brick and concrete, everywhere at least five times a man’s height. A steep-sloped ditch ran along the north side. It was clogged with rubbish and weeds—and in some places the detritus of battles, broken sword blades and dented shields and smashed wheels; sometimes the hairy folk from the north would creep down to scavenge bits of iron. To the south, beyond the line of the road that ran parallel to the Wall, was another broad trench called the vallum. The vallum had been filled in here and there, to provide easier access between the fortresses on the Wall itself and the muddy little community of huts and roundhouses that had, over the generations, grown up to the south.

It was thrilling to think that the Wall’s great line was drawn right across the neck of the country. On a clear day she could see the sentries walking back and forth along its length, all the way to the horizon, like ants on a bit of string. And while on the north side there was nothing but moorland, heather, and garbage, on the south side there was a whole string of communities, inhabited by the soldiers and their families, and those who lived off them. It was like a single town, some of the soldiers said, a Thin Town eighty miles long, a belt of drinking and whoring and cockfighting and gambling, and other vices she understood even less.