The air in here has to travel somehow. The whole Keep must be honeycombed with shafts too small for a man to fit through. But the Dark can change their size as well as their shape. They could fit through a hole no bigger than a rat's, and, God knows, we have rats in the Keep. All it would need would be for one of them to get into the ventilation -the thing could attack at will, and we would never be able to find it.'

'Curse it,' Janus whispered, 'that the Dark should rise at the start of the worst winter in human memory. If we quit the Keep, those as aren't taken at first nightfall would freeze before they came to shelter. These mountains are buried in snow.'

'Rats...' Tirkenson said softly. 'Ingold, how do we know the

Dark aren't lurking somewhere in the upper levels already? The Keep stood empty for nigh two thousand years.'

'We would have known,' the wizard said. 'Believe me, we would have known by this time.'

'But their eggs?' Tirkenson went on. 'How do the Dark Ones breed, Ingold? As Gil-Shalos said, it would need only one to go through the air tunnels, laying eggs like a salmon along the way. We could be sitting on top of a spawning ground of the Dark.' Though the Guards were not as a rule nervous people, a ripple of horror seemed to pass through the assembled captains. The instructor Gnift shuddered and exchanged a quick, worried look with Melantrys.

'You needn't concern yourselves with that, at least,' Ingold said quietly. He picked a bit of straw from the frayed sleeve of his mantle and avoided all their eyes. 'I have seen the breeding places of the Dark beneath the ground, and I assure you that they do not multiply in any fashion so - tidy - as that.' He looked up again, his face carefully calm. 'But in any case, we cannot allow the Dark entrance under any circumstances. The corridors must be patrolled.'

'We can get Church troops,' Janus said, 'and Alwir's private guards.'