Narses was on his feet before the others. Right hand flat on his chest, in the Latin of the camp, he recited the sacramentum. ‘By Jupiter Optimus Maximus and all the gods, I swear to carry out the Emperor’s commands, never desert the standards or shirk death, to value the safety of the Emperor above everything.’

One by one, the mismatched assortment of soldiers repeated the oath.

‘Now you will give me the tokens that identify you as secret soldiers.’

Silently, the metal disks carrying the words MILES ARCANUS were handed over to Severus.

‘Until tomorrow morning at the inn of Antiochus,’ Severus said. ‘Remember, from now on we have nothing but each other.’

Chapter 5

CHAPTER 5

The Euphrates

BY THE BRIDGE WAS COILED a large chain, ivy and vines growing through its links. It was said to be very old, from the original crossing of the river by Alexander the Great, or even the god Dionysus on his way to India. Whichever, the queue waiting to cross to the east bank had given Valens far too much time to contemplate its supposed antiquity.

‘Not long now,’ Iudex said. ‘The ships have gone through, and the pontoons will soon be back in place.’

Valens studied the chain. It was remarkably free of rust for something claimed to be so ancient. Evidently the Persians had not thought it worth looting when they sacked Zeugma.

‘This delay is nothing.’ Hairan sat in the shade, his elegantly trousered legs crossed. ‘Before the fall of Hatra, the street would have been solid with caravans. The warriors of my city kept the routes through Mesopotamia safe. The land between the two rivers was full of camel trains. Silks and spices, lapis lazuli and turquoise, transported from the distant east; sweet white wine and unguents in delicate alabaster from the west; the most beautiful concubines from across the world – all the good things in life flowed through Zeugma.’ The young Hatrene gestured dismissively at those waiting to clear the customs post. ‘These are no more than peddlers, or peasants bringing things to market.’

‘How many years since Hatra fell?’ Iudex asked.

‘Twenty-five years since the evil fell across the land.’

Iudex was smiling. ‘And you are how old?’

Hairan stretched like a cat. ‘I was a child, but it is like yesterday. We men of Hatra have long memories. One day we will have our vengeance.’

For a time they sat without talking, listening to the slop slop sound of screws raising water into the town from the river.

Severus had crossed over before dawn, before the pontoon bridge had been opened to let the boats downriver. He would meet them at the first milestone beyond Apamea. It was beneath the dignity of a prosperous merchant to wait with the rabble in the street. He had left his nephew in charge of the caravan.