The wind picked up. A new volley of snow slammed against the north-facing side of her cabin, so solid and dense that from her windows she could see nothing but driving flakes coming at her from grey infinity, like one of Nelo’s look-deep drawings. The cabin shuddered and creaked, rocking slightly. She clutched the rim of the padded wooden bench on which she sat, and wondered when the engineers would get the caravan moving again.

When the snow started to come down Mago was taking a walk along the Wall Way, the broad track that followed the foot of the Wall. There was some flooding here – had been for days, it seemed, maybe the big mechanical pumps the Northlanders boasted about weren’t working so well – and you had to watch where you walked.

But the Wall itself loomed above him, busy as ever, crowded, complicated, a vertical city that stretched to left and right as far as he could see. Today was some kind of market day, and stalls had been set up before the row of shops, manufactories and warehouses along the Wall’s lowest run, just wooden posts fixed into slots in the growstone walls and then draped with big awnings of cloth or leather, a simple way to increase selling space. And now, even though the whole area was stuffed with nestspills – pathetic little groups of them, whole families sitting in the dirt, empty hands held out in the cold – the grand folk of Etxelur were out shopping for jewellery and shoes, and dishes and cutlery and pots and pans, and knick-knacks brought here by traders from across the known world.

Mago had been in Northland for four months now, and since his uncle Barmocar had taken so long to close his negotiations over supplies to Carthage of Etxelur’s disgusting salted fish, it looked as if the weather was going to close in and they would be stuck in this dismal lightless hellhole for the winter. Well, Mago wasn’t going to be intimidated by the mighty Wall, even though he knew intellectually that you could take all of Carthage and its environs, wad it up and stuff it inside the Wall’s great carcass, and it would be utterly lost. For, he had learned, the Wall wasn’t quite the symbol of smug unity some Northlanders would have you believe. The Wall was so vast that you had to think of it as being many communities, several cities with separate traditions, even separate customs and dialects, all joined in this one giant structure. And at least once, he had heard it murmured, there had been an intramural war when one of these culturally distinct blocks had defied the will of the rest – a War of the Districts – but you wouldn’t find any reference to that in Northland’s official histories.

The snow fell suddenly, just dropping as if somebody had emptied a tremendous bucket over his head.

Shielding his eyes and looking up, he saw that it was coming from the north, the ocean side, big fat flakes swirling over the Wall’s parapet and billowing down in sheets to the ground below. Already it was gathering on the ledges and protrusions and buttresses of the Wall’s upper surfaces, and on the roofs of the structures below. And Mago had come out without a hat.