‘They are not to be trusted.’ Clemens wiped his small, stubborn mouth. ‘I served out here, in Syria Palestina with the Sixth Legion, the Ironclad.’

‘But Narses and the others have taken the military oath,’ Valens said.

Clemens leant out from the saddle and spat. ‘Narses is a renegade. The Persian has betrayed his own people. He would not hesitate to do the same to us.’

‘Zabda?’

‘You should know, the Palmyrene is a thief. If that madman Iudex had not intervened, most likely he would have killed you. Palmyra is a desert shithole. Without Persian trade, it would not exist. Zabda’s countrymen serve in the armies of the King of Kings, hold office in the cities he rules.’

‘Hairan seems sound.’

Clemens snorted. ‘An exile from a destroyed city, a mercenary who sells his sword to the highest bidder, no family and no home to keep him loyal. Dresses like a Persian, speaks Persian, look at him.’

Ahead, through the dust of the caravan, Valens could see Hairan where the plain once again reached the hills. The bright colours of his loose tunic and wide trousers shimmered in the heat.

Clemens turned away, bringing the conversation to an end.

Like the mules, they followed the tinkling bell into the hills. The high country was bunched and cut by ravines. The surface of the track was white and powdery. It raised a fine grit, which worked its way into eyes, mouth and nose. The path twisted and dipped, crossed and recrossed dry watercourses. Naked slopes rose on all sides, shutting off the view. When they crested a rise, and the vista opened up, it revealed nothing but miles of yellowish-brown rock, turning pinkish in the distance with the heat of the afternoon.

When the sun was halfway down the cloudless sky, Valens began to think that it would soon be time to make camp. He was hot and tired. With fatigue the column had become stretched out. It was difficult to estimate how far they had travelled – about ten miles from Carrhae to the hills, after that possibly another fifteen along the track. Given the circuitous course of the latter, they would not have covered half so far towards the east.

Clemens was muttering under his breath. The armourer had given up swatting at the flies and was gazing around at the slopes. Perhaps he too was wondering how long before they would halt, was looking forward to a rest, and something to eat. It occurred to Valens that Clemens was no longer young.

‘How long have you been with the standards?’

Clemens did not look at Valens. ‘Twenty-four years.’

‘What will you do when you are discharged?’

‘I had intended to buy a small farm with my retirement bonus next year. Somewhere quiet, like Calabria or Apulia. Take my family out of the city.’

‘You had intended?’

Clemens glanced at Valens. ‘I do not think we will return from this mission.’

‘We will do our duty.’