By now it was the dead of night. Nelo had been working flat out, like everybody else, since he’d first come here to the Hall of Annids, and he had no precise idea of the time. Doctor Ontin had got his emergency hospital running pretty quickly. Mago and Nelo had been used as spare muscle in Ontin’s scheme to sort out the continuing trickle of injured and ill as they kept arriving through the night. Ontin himself, with other surgeons and nurses, was working hard on the more serious injuries, the broken limbs and crushing wounds, the frostbite, the cases of exhaustion, even a couple of heart attacks.

Things had got steadily worse. The heating had been off for hours, and the running hot water. Then even the cold water supply had failed, then the gas supply that fed the lanterns. Ontin, bossy, exasperated, had coped with all this as it had unfolded, barking out commands to anybody who would listen, including Ywa Annid of Annids, who made sure that what he wanted got done. Soon the Hall was studded with candles, and open fires blazed in antique hearths unused for a century. Clogged chimneys trapped smoke and the ash, and there wasn’t much to burn save smashed-up furniture – it was very expensive firewood – but the fires gave out enough heat to keep them all from freezing altogether.

But all through the night Nelo and Mago, remembering their adventure with the awning, had kept an eye on that roof, a great glass lid over them all, that had been covered with snow thick enough to block out the daylight even before the sun had set. In the dark it was easy to forget about, you couldn’t even see it in the flickering light of the candles. Nelo had tried a couple of times to warn Ywa about the problem, but she hadn’t really listened, and he understood; you couldn’t deal with everything at once. But the two of them had kept watching, and listening.

It was Mago who heard the first pane crack, even over the noise of the hospital, the cries of the injured, the squalls of babies, the general susurrus of conversation. He grabbed Nelo’s arm, almost making the Northlander drop the bundle of blankets he’d been carrying. ‘Look,’ he snapped in Greek. ‘Up there . . . near the centre . . .’

The roof was barely visible in the candlelight. But Nelo, squinting, made out the latticework of iron strips that held the panes in place, and the panes themselves grey with snow. And there, yes, in the centre, he saw a spiderweb of cracks.

‘I don’t know what’s holding it up,’ Mago said. ‘If one pane fails—’

‘The rest will follow.’

‘It’s just like that accursed awning again.’ He shook Nelo’s shoulder. ‘Come on, Northlander. These are your people. Make them listen!’

And then another pane cracked, more loudly. All around them people looked up.