The Castle of Silence was set on a razor-backed ridge. A road ran up to its gatehouse from the west. It was steep and utterly exposed, but smooth and wide enough for a wagon. The outer wall of the fortress, roughly oval in shape, was built right on the edge of the two precipices. At the far end from the gatehouse, built into the circuit wall, was a tall round tower. From a postern hidden behind the tower, a narrow track snaked down the slope and vanished to the east.

Every detail was clear in the early morning sun. From the cliff to the north they had a good view across the ravine. And everything they saw was depressing. The gates were kept closed. The battlements above them were patrolled. While the sides of the ravine did not look unclimbable, and a few shrubs would provide a modicum of cover, even at this distance it was clear that the wall, constructed of well-jointed masonry, could not be scaled without a ladder or grappling hooks.

‘You once served here, Narses, tell us about the routine.’ Valens kept his voice down, even though, with the wind keening over the rocks, there was no way anything but a shout could possibly be heard across the void.

‘The guards are replaced every two months,’ Narses said. ‘Any longer up among these crags, and they would go off their heads. Only the gaolers who do the torturing stay all the time, and they are demented anyway.’

‘How many?’

‘Twenty guards come up from Hyrkania. There are about half a dozen who wield the hot knives and turn the rack.’

‘Domestic staff?’

‘A dozen or so stable boys and cooks and the like. They never leave.’

There were far too many either to storm the place or ambush the relief. Access would have to be by some more clandestine method.

‘Who else comes and goes?’ Valens asked.

‘Occasionally the zendanig is summoned to court.’

‘The zendanig?’

‘The warden of the prison. Cruel bastard with a big red beard, always wears black. Even inanimate objects seem to fear Naduk the zendanig.’

Decimus thought of something. ‘You said you caught a leopard when you were here.’

‘Once in a while the zendanig will give a couple of the men leave to go hunting. The gates are bolted behind them, and they are not let back in until they have been recognised. No one dares open the gates without Naduk’s order.’

‘What do the soldiers do for women?’ Decimus asked.

‘Usually four or five whores in the place.’ Narses shook his head sadly. ‘Poor bitches get melancholy, and their looks start to go. While I was here, one threw herself off the wall.’

‘Too much used?’ Decimus said sympathetically.