Crimm touched his arm. ‘Leave it. It’s the mirrors or nothing.’ Crimm shared many of Ayto’s doubts about the wisdom of the Annids’ strategy. Who wouldn’t? But even if all was lost today, as Ayto knew very well, the two of them, and their families, had their bolthole, in the abandoned cistern deep inside the Wall. Though Crimm still had not decided how he would deal with his relationship with Ywa, if that dire choice had to be made.

‘They’re getting close!’ somebody called, higher up the Wall face.

They all stared out, shielding their eyes against the glare.

The mob was making slow progress, struggling in drifts that could be waist deep. The fresh-fallen snow had been purposely left uncleared before the Wall for many days now – another line of defence. The attackers were just bundles of filthy cloth and fur, armed with hunting knives and clubs and spears, breathing hard as Crimm could tell from the misting of their breaths. There was no sign of any military discipline, any formation. But there were an awful lot of them. Folk the colour of mud against the snow.

Crimm turned to the Annid. ‘Ywa, it may not be safe here much longer.’

‘I will not leave. Whatever the outcome, Crimm, something of old Northland dies today. Never before have we turned on each other on such a scale. And I must be here to witness it . . . I cannot believe it has come to this so quickly. But then, I suppose, each of us, however grand, has only ever been a few missed meals from the animal.’

Crimm glanced up at the sun, at the position of the advancing crowd. ‘Time for the scholars’ weapon, I think. We’re lucky with the sun being so bright.’

Ayto snorted his contempt. ‘We’ll be lucky if this stunt makes any difference at all. Typical scholars! Strike at a distance and hope you never have to close with the enemy at all.’

Crimm understood his cynicism. Yet he hoped in his heart that the scheme worked, and the horror of a close fight could be averted.

It was time. He heard the clear voice of Annid Xree calling out final instructions. ‘Be ready to cut the banner ropes . . .’

Crimm leaned over the rail. All over the Wall face people came forward to the balcony rails, ordinary folk, clerks and cleaners and barkeeps, looking down nervously at the approaching horde, whose angry cries could already be heard. They held their places, their knives and axes poised.

Xree called, ‘On my three. One – two . . .’

A hundred arms, raising axes and blades.

‘Three!’