It was universally agreed that the single most spectacular location on the Iron Way east of Northland, if you discounted the run along the parapet of the Wall itself, was the viaduct that spanned the great estuary of the World River. On this viaduct now, heading back west towards Northland, Alxa could peer out of the thick glass windows of her cabin and look north over the ocean, or south over the mighty river itself, its broad body studded with shipping, its banks clustered with docks and towns, the country beyond incised with fields and drainage ditches. But this morning Alxa couldn’t appreciate the view at all.

For one thing the caravan had been stuck here for an hour, right in the middle of the viaduct. The officer who had come to check on her steam-fuelled heating box had told her that the engineers had decided to stop and fit snowblades. Snowblades, this early in the season! What a waste of time – so she’d thought. And yet she had to admit the engineers had been right, for even while the caravan had been waiting the clouds had bubbled up from the north, and the first big fat flakes had come swirling in to slap against the small panes of her windows.

On top of that, her head was still full of the arguments she’d had with her mother about Great-Uncle Pyxeas. As she’d grown to know the old man who had come back into her life at the midsummer Giving, she’d come to admire him hugely. Alxa was fifteen years old. She wasn’t sure what she wanted to do with her life, not yet, and as far as she could see, as the weather closed in on the world, her options were diminishing. But she had felt she wanted to help Pyxeas, if she could. She didn’t understand his developing theories, and she didn’t quite believe his doom-laden warnings of a frozen world – or maybe, a small voice nagged, she didn’t want to believe them. But at least this increasingly frail old man was trying to understand, as he had been for all his life, including the three years he had spent shivering his arse off in Coldland, trying to scry the mechanisms that drove the changing world, with his peculiar muddle of astronomical wobbles and a dance of sea and air.

Then, as a horrible summer ended and a worse winter started to close in, he had shot off to Cathay! She had wanted to go with him, to help him on his journey, but her mother wouldn’t allow it. That had caused a huge row, and in the compromise that emerged her mother had ended up disappearing to Hantilios with Pyxeas, while Alxa had been given the consolation prize of a trip to the World River, as part of an Annid mission that Rina had been supposed to support. It had been a marvellous journey, but it didn’t resolve anything.

And now, trying to get back, here she was, stuck, alone, far from home.