‘Go and you’ll die.’

Arrian jumped with surprise, and Rufus might have found some comfort in this display of weakness if he had not once again yelped like an infant. The voice had spoken in Latin and had come from their left. Yet he could see nothing there, apart from the dark mound of the old wall.

‘Herakles’ balls,’ Arrian said softly. ‘Who are you? Speak!’ His voice only wavered a little and Rufus was once again impressed by the tribune. His own heart was pounding. After a moment, thinking that something more practical was in order, he started to fumble beneath his sodden cloak, searching for the hilt of his sword. He could still see no sign of anyone in the darkness, nor had the voice spoken again.

‘Do you hear me?’ Arrian sounded steadier now. The tribune managed to flick aside his cloak more smoothly than Rufus, but did not make a move to draw his gladius. ‘Show yourself! Who are you? What do you want?’ The tribune had switched to Latin, which had only a hint of the sing-song accent common to Bithynia.

Rufus fumbled until he had his fingers around the bone grip of his sword. The cloak had fallen back over his hand, so he tried to inch the blade out of its scabbard. It would not move, probably rusted by the rain.

‘If you go down there, they will kill you,’ the voice said flatly. ‘Doesn’t matter all that much to me, unless you make them wonder who else is up here.’

‘They’re our men.’ Arrian was so exasperated that he had gone back into Greek, probably without noticing.

‘They’re slavers.’ Rufus thought that he caught a hint of Gaul or even further north in the man’s speech. ‘They’ll kill you just to take your boots – and that fine sword and armour. Be a good night’s work as far as they are concerned.’

Arrian drew his gladius. Rufus decided to ask him whether he had greased it with anything special, for it came free with only the slightest hesitation. ‘We are in a Roman province,’ the tribune declared, ‘and there are thousands of soldiers not far away from us.’ Rufus had to wonder whether or not that was true, although he guessed it was still possible. ‘Why would slavers be here?’ the tribune asked.

‘Coming home from Cyrrhus. They’ve sold the people they kidnapped in Assyria and Media. Snatched a few strays on the way to sell once they were over the river and in Osrhoene or beyond. Lot of opportunities for bold men willing to cross between empires and kingdoms.’

‘Indeed. And you know this?’

‘I do. Killed one of them a few hours ago. Wounded his mate, who was willing to talk.’

‘Before you executed him?’ Arrian asked.

‘No. The deal was for him to live if he talked. He is injured, unarmed and on foot. He might make it, or he might stumble into some villagers or shepherds. They’re not keen on slavers.’