‘Sir.’ Decimus approached. It was midday, and the pall of dust had been spotted to the north.

They saddled up quickly with the efficiency of long practice.

‘How many Arabs were left in the camp?’ Decimus asked.

Valens calculated. He and Iudex had both killed a pair, and Zabda had dealt with the sentry. The arrows of Narses had accounted for three more. ‘No more than seventeen.’

‘That cloud is raised by at least thirty.’

‘Then it might not be them.’

‘Or they have found some friends. These deserts are full of the bastards.’

‘We will turn south-east. The mountains we have to cross are in that general direction. Sooner or later we should strike the river we need to follow. At Nineveh they said it ran down from the heights.’

There was no panic. For the first mile they went at a walk to let the animals warm up. As ever they then halted briefly to check the girths of their mounts and the rigging of the mules. After that they proceeded at a trot, the baggage animals ambling. They still made good ground, and their relatively gentle progress left less telltale dust behind them.

After another hour, at the next halt, it was evident the other riders had turned after them. The pursuing column of dust was appreciably closer, perhaps no more than a couple of miles to the rear.

Valens sat his horse, studying the sky, thinking.

‘We should get going, ride hard.’ Decimus said. ‘The mules will not be able to keep up. We must abandon them.’

‘Not yet,’ Valens said. ‘We have a head start. If we alter course south-west, and they turn after our tracks, then we can be certain that they are hunting us.’

‘But that is away from the mountains.’

‘If we continue south-east, we may reach the foothills before we find the river.’

Decimus looked dubious, but did not argue.

‘Without the river to guide us up to the pass, we may be trapped against the mountain wall.’

Decimus gave a curt nod, and circled his horse back to his station.

Within half an hour they knew the worst. Again the hateful column of dust dogged them.

Valens raised his arm to halt the small column.

‘Take from the baggage train whatever grain and water your horses can carry. Load some supplies onto the sound spare horses. We will leave the mules, and the lame horse.’

‘Why leave the mules for the camel-fuckers?’ Aulus said. ‘We might as well slaughter them.’

‘And the lame horse will recover,’ Clemens said. ‘I hate to think of a nomad riding him.’

‘No,’ Valens said firmly. ‘They may be satisfied with their booty.’

‘And they may not,’ Hairan said glumly.

The provisions were speedily stowed on the horses. It would leave them short, but it was no time to worry about that.