It was a miracle that the expedition had got this far. None of his plans had come to fruition. Once Valens had appointed Decimus second in command, there had been no point in killing the young officer. In the mountains before the Castle of Silence he had written a warning, in both Greek and Persian, betraying everything he knew about the mission. He had tied it to an arrow. Setting off to hunt those wild goats, he had intended to shoot it over the wall. It would have been difficult to approach the walls unseen by either the garrison or his own companions, yet he was sure it could have been managed. Once inside, the others would have been taken, and he would have been rewarded. And then that fool had insisted on accompanying him. At the ambush of the supply wagon there had been nothing at all to be done. Inside the castle, the enforced intimacy of the barracks had left him unable to find an excuse to slip away from the watchful eyes of the others. As they rode out of the postern, he had dropped the arrow with the writing still attached to its shaft, but doubtless it would have been consumed in the fire.

Yet the Persian cavalry patrols out on the plains indicated that one of his schemes had not failed utterly. The expedition would have outrun the news from the Castle of Silence, but the garrison of the Walls of Alexander had been alerted. The local he had paid back in Zadrakarta had not played him false, but had delivered the letter. The garrison was watching for them. The problem was that the Walls of Alexander stretched for hundreds of miles. In Zadrakarta he had not known where or how Narses intended to get them across the border.

A torch flared in the distance as a sentinel walked out onto the battlements of the fortress.

For a moment he had the urge just to run towards the light, shouting, to get this treachery over with. The notion was ridiculous. Narses was crouched a few paces away in the reeds. He had never seen a better shot than the Persian. And there was no point in bringing destruction down on the mission, if he himself did not survive.

How had it come to this?

It was his own fault. His position of trust in the Camp of the Strangers had made it easy to take the money. Tullia’s family were poor, her father’s business not doing well. They needed the money. A few strokes in the ledgers and the money had vanished from the army. Everything had been fine until that shrewd little bastard Murena had been appointed.

No, it was not his own fault. It was Murena. Even had the commander of the frumentarii not uncovered the fraud, his threats would have been more than enough. Murena knew that rather than see Tullia hurt, he would betray the entire world.