An experienced mountaineer, Aulus had been the obvious choice for the expedition. Valens had a good head for heights, but the Gaul might be an aid if the climb was difficult. They had brought ropes and metal spikes to act as pitons. They coiled the former over their shoulders, and secured the latter, along with a torch each, on their sword belts. The long swords themselves would have been an encumbrance, but it was unwise to be entirely unarmed. They kept their daggers. This high in the mountains there was always the chance of encountering a leopard or bear.

‘Shout if you see an empusa,’ Clemens said. ‘They do not like loud noises. Philostratus recorded that was how the holy man Apollonius of Tyana scared one away.’

‘The Life of Apollonius is fiction,’ Valens said. ‘At one dinner the utensils and serving dishes start moving by themselves.’

‘This is a fool’s errand,’ Iudex said.

At least, Valens thought, one of the men does not share the general superstition.

‘There is no empusa here.’ Iudex said with complete certainty. ‘Last night, while you all squandered the divine light in your semen on slave girls, my spirit-twin searched the whole mountain. It found nothing.’

Gods below, Iudex was the worst of the lot.

At first the ascent was easy. They were able to step around more of the large boulders that had fallen from above than they had to clamber over. When the rock under their feet was not solid, the scree was bound together by tough mountain grass. Aulus set a fast pace for a man who must have been in his forties, probably approaching retirement from the army. Soon, Valens was sweating and blowing hard.

When they came to the steeper slopes, Aulus called a halt and sat down. He regarded Valens with his rheumy eyes, a smile on his ill-favoured face.

‘Tired yourself out with that serving girl,’ he said.

Valens shrugged. ‘Only inclination held you back.’

Aulus nodded, accepting the truth of the statement. ‘It is strange. Among us no one thinks the worse of a man for enjoying a slave boy. No harm done, no one gets hurt. But these Persians call it an unnatural lust or sinful copulation. Their laws are harsh: a whipping or death. Apparently, in their underworld, such sinners are punished with snakes crawling up their arses and out of their mouths. Not a pleasant way to pass eternity.’

‘You speak Persian?’

‘A little, and some Aramaic. I was stationed in the east for a time. If you are rested, we should get on.’