The doctor swallowed hard. 'A soldier from the numerus of Ogelos, Kyrios, one of the conscripted townsmen.' The man stopped. He was sweating.
'Why did he come to you?'
'Two of his fellow soldiers brought him, Kyrios. They had taken him to the doctor of the numerus, but he was drunk.' The man stood straighter. 'I never drink to excess, Kyrios.' He beamed at Ballista. He was still sweating.
'And did you find out where he was when he was hit?'
'Oh yes, his friends told me. They said that he had always been unlucky. He was not on the wall, not even on duty. They had been drinking in The Krater all evening. They were on their way home, back to the tower just east of the postern gate. They were crossing that bit of open ground when, whoosh, out of the darkness, the arrow came down over the southern wall and hit him in the shoulder.'
'Did he survive?'
'Oh yes, I am a very fine doctor.' His tone betrayed his own surprise at this outcome.
'I can see that.' Ballista stepped towards him again. This time he came right up to him, using his size to intimidate. 'You will not mention this to anyone. If I hear that you have…' He let the threat hang.
'No, no one, Kyrios, no one at all.'
'Good. Give the soldier's name and that of his friends to my secretary and you are free to go. You have played the part of a conscientious citizen very well.'
'Thank you, Kyrios, thank you very much.' He virtually ran to Demetrius, who had his stylus ready.
There was a loud tearing sound of something big travelling fast through the air followed by a huge crash. The doctor visibly jumped. A fine trickle of plaster came down from the ceiling. The artillery duel had been going on for six days now. Clearly the doctor had no desire to be as near to it as this requisitioned house close behind the western wall. As soon as he had gabbled the names of the soldiers, he turned and fled.
Demetrius folded his writing block and hung it back on his belt. He picked up the papyrus again and studied it. To give him time, Ballista walked across the room and poured some drinks. He gave one each to Mamurra, Castricius and Maximus, put one down near the secretary and, sitting on a table, began to sip his own.
There was the awful sound of another incoming artillery stone, another crash, and again a fine drizzle of plaster. Mamurra commented that one of the Persian stone-throwers was overshooting. Ballista nodded.
At last Demetrius looked up. He smiled apologetically. 'I am sorry, Kyrios. I cannot make out the code. At least not straight away. Most codes are really very simple – you substitute the next letter in the alphabet for the one you mean and the like; sometimes even simpler: you make a small mark by the letters that are meant to be read, or you write them at a slightly different level from the others – but I am afraid that this does not seem to be so simple. If I may I will keep it and study it when I have no other duties. Maybe eventually I will unravel it.'
'Thank you,' said Ballista. He sat and drank, thinking. They all sat in silence. At intervals of about a minute there was another crash and more plaster drifted down to add to the fine dust which covered every surface.
Ballista once more felt the lack of Antigonus; he would have been ideal for what Ballista wanted done. Mamurra was already too busy; Ballista wanted Maximus with him…
'Castricius, I want you to talk to the three soldiers. Find out exactly when and where the man was hit. Swear them to secrecy. Threaten them a little to make sure they do not talk. You had better be quick talking to the wounded one before he dies of some infection.'
'Dominus.'
'Then pick three of the equites singulares and have them keep a discreet watch on the area. It is too much to hope that one of them will be hit by an arrow with a coded message tied to it, but I want to know who they see in that part of town.'
Again the standard-bearer simply said, 'Dominus.'
'Anyone hanging around there might be our traitor looking for the message he was expecting but never received. At least now we have positive proof that we still have a traitor among us.'
A crescent moon hung low on the horizon. Above, the constellations slowly turned – Orion, the Bear, the Pleiades. It was the fifteenth of August, the ides. Ballista knew that, if they were still alive to see the Pleiades set in November, they would be safe.
It was deadly quiet on the battered south-west tower of Arete. Everyone was listening. Usually it seemed unnaturally quiet in the evening when the artillery duel ceased for the day but, now, as they strained to hear one particular sound, the night outside the tower was full of noise. A dog barked somewhere in the town. Nearer at hand a child cried. Faint noises drifted across the plain from the Sassanid camp: the whinny of a horse, a burst of shouting, snatches of a plaintive tune picked out on a stringed instrument.
'There, do you hear it?' Haddudad's voice was an urgent whisper.
Ballista could not hear it. He turned to Maximus and Demetrius. In the dim light they both looked uncertain. They all continued to strain their ears. The night grew quieter.
'There, there it is again.' The voice of Iarhai's mercenary captain was even softer.
Now Ballista thought he half heard it. He stilled his breathing. Yes, there it was: the chink, chink sound Haddudad had described, gone as soon as the northerner heard it. He leant out over the parapet, cupping his hand to his right ear. The sound was gone. If it had existed at all, it was covered by the noise of a Persian patrol making its way along the southern ravine. The scatter of stones dislodged in the near darkness, the creak of leather, the clang of metal on metal – all rang loud. They must have reached a picket. The listeners on the tower heard the low challenge 'Peroz-Shapur' and the answer: 'Mazda.'
Ballista and the others shifted their positions and breathed deeply as they waited for the patrol to pass out of earshot up on to the plain.
The volume of the night resumed its normal elusive texture. An owl hooted. Another answered. And in the silence that followed, there it was: floating up from somewhere' down in the ravine towards the plain, the chink, chink, chink of pickaxe on stone.
'You are right, Haddudad, they are digging a tunnel.' Ballista listened some more until somewhere behind him in the town a door opened and a burst of laughter and raised voices obliterated any other sound.
'We should send out a reconnaissance party. Find out exactly where it starts. Then we can estimate the route it will take.' Haddudad still spoke in a whisper. 'I would be happy to go. I can pick the men in the morning and go tomorrow night.'
'Thank you, but no.' Ballista had been about to call for Antigonus. Then he remembered. He thought for some moments. 'We cannot wait until tomorrow night. If we make any preparations for a scouting party the traitor may find a way to warn the enemy. Our men would walk into a trap. No, it must be tonight, now. I will go with Maximus.'
There was a collective intake of breath, then several voices spoke at once. Quietly but determinedly Demetrius, Haddudad and his two sentries in their different ways said that this was madness. Maximus said nothing.
'I have made my decision. None of you will speak of this. Haddudad, you and your men will stay here. Demetrius, go and find me some ashes or burnt cork and meet Maximus and me at the southern postern gate.'
Haddudad and his men saluted. Demetrius hesitated for some time before going down the steps.
By the time Demetrius had fetched the camouflage from the requisitioned house that served as military headquarters and reached the postern gate, Ballista had told the plan to Cocceius, the decurion in command of the turma of Cohors XX stationed there. Ballista and Maximus were going to leave by the gate. It was to be left open until dawn. Then it was to be shut. It was not to be opened again unless the Dux Ripae and his bodyguard appeared before it in daylight, when the guard could be certain they were alone. In the event of them not returning, Acilius Glabrio was to assume command of the defence of Arete. Ballista had written a short order to this effect.
'Sure, is that not enlisting the wolf to be your sheepdog, thinking as you do that he himself might be the traitor?' Maximus had said in Celtic.
'If we do not come back, I think we will be past caring about that,' Ballista had replied in the same tongue.
Ballista prepared himself. He took off his helmet, mail coat and the two decorations on his sword belt – the
