Valens gazed back the way they had travelled. The hard scrabble over which they had ridden raised little dust. There was no sign of pursuit. Something caught his eye. Something out of place in that elemental wasteland. He squinted in the late afternoon sun.

‘What fool dropped a water bottle?’ Valens rounded on his men in fury.

None avoided his eye. One or two spread their hands in a mime of innocence.

‘Why leave a trail for them to follow?’

The anger died out of him. ‘Just take more care,’ he muttered. ‘Check the horses, the saddlebags and stowage as well as the tack, before we move on.’

There was no further indication of pursuit before the light faded. But two more horses, those of Aulus and Decimus, went lame. It was not to be wondered at; the animals had been hard used. Neither was broken down, and both could still run on a lead. It did mean there was only one spare ridable horse left, and a further redistribution of their much diminished stores. After the column pulled out, Valens hung back with Hairan, and checked that nothing had been dropped or cast aside that could mark their sojourn.

After the sun had set, the water of the river still held a faint luminescence of the day. They had reached the Lykos, and the nomads had not caught them. The road to the pass was open before them. All they had to do was follow the river upstream. The waters would cover their tracks. In the upper reaches they could find a local to take them over the watershed. It felt like a pivotal moment.

‘How do we know this is the right river?’ Aulus’s question crushed Valens’s temporary joy.

‘What other river can it be?’

‘Any number of streams must run down from the mountains to the Tigris.’

‘The stars indicate we are at the right latitude.’

‘The stars are malign,’ Iudex said.

The woman walked up to where they stood. ‘It is the Lykos.’

‘How do you know?’ Aulus asked gently. Like all the men, her suffering was on his mind.

‘My husband and I followed it down from Matiane.’

Inwardly Valens cursed himself for a fool. How else could the ill-fated trader have crossed the mountains to meet his fate in the desert? Because she was a woman, it had not occurred to any of them to ask her advice.

‘We have our guide,’ he said.

The soldiers laughed, although Iudex put his thumb between his fingers to avert evil. In his religion women were as inherently evil as the stars.

‘Can we take the horses up the riverbed?’ Valens said.

‘I do not know. We brought the wagon down the track alongside the river,’ she said.

‘Well, we will soon find out.’