‘Now we ride due south. There are only some three hours of daylight left. They will never catch us before dark.’ Valens spoke with far more certainty than he felt.

They did not set off at a mad gallop. That risked accidents, and would soon exhaust their mounts. Instead Valens kept them to a steady canter which ate up the miles.

For the first hour all went well. Valens reined in, and looked back. The Arabs would have been pushing their mounts for longer than the soldiers. Valens and his men were pulling away. But the column of dust was still following. The mules and what they still carried had not been enough to placate the vengeance of the tent-dwellers.

‘Persistent, aren’t they?’ Valens muttered to no one in particular.

‘The nomads live by blood feud,’ Hairan said. ‘We have killed seven of them, they are bound to kill seven of us.’

‘Well, as long as I am the one left alive,’ Clemens said in a rare moment of black humour.

‘Give the horses a drink, and then we press on,’ Valens said. ‘Not long until darkness, and we must be getting near the river.’

The ground here was more rock than sand. The hooves rattled in the steady, almost soothing rhythm of a fast canter, the easiest gait for both horse and rider. The noise and the motion lulled Valens into something approaching a reverie. He had the odd impression that they were unmoving, that the sky wheeled overhead, and the desert raced away behind them. In this altered state, his thoughts moved unbidden to dark, unhappy things.

Interfectus a latronibus. You saw the inscriptions all over the empire: Killed by bandits. You passed without a thought. Until the victims were those you loved. There were many bandits in Italy. The Apennines were full of them. Many were barbarians, stragglers from the Alamannic invasion five years ago. Had they tortured his father before they killed him? Had they raped his mother before they killed her too?

Killed by bandits. He had set up the stone by the mountain road beside which the bodies had been found. They had lain there for some time. It had been impossible to judge how much they had suffered.

A harsh shout, and a break in the rhythm of the horses, brought him back. Valens pulled on his reins.

The woman had fallen. She was lying, groaning on the ground. Zabda and Clemens were already dismounted at her side.

‘I can’t go on,’ she said. ‘Don’t let them take me again. Please, put me out of my misery.’

Zabda hushed her, and looked up at Valens. ‘She is not badly hurt. She can ride with me.’

‘Make sure to switch to a spare horse every half-hour,’ Valens said. ‘Otherwise the extra weight will slow you down.’

Clemens helped Zabda hoist her up in front of the saddle.