‘Do you want to give me something to take to him?’

‘Worse yet. If they catch you and search you, what will you say? They’ll cut you into little pieces, one piece at a time, until they’ve got every scrap of information from you. I’ll take care of this. I’m not sure how, but I’ll take care of it. Sooner or later they’ll have something better to do than keep me confined here. Do you understand what you’re to do?’

‘I do,’ answered the boy.

Artemidorus opened a drawer and took out a little piece of parchment. ‘This is a prescription Antistius gave me. It’s a cure for constipation. He’ll recognize it and be sure that I’m the one who has sent you. If you’re stopped on your way, no one will have reason to scold you or suspect you of anything. If Antistius asks about me, tell him that I’m not free to move but that as soon as I can I will contact him personally.’

‘I’ll go first thing in the morning, then.’

‘Go, and good luck. If everything turns out as I’m hoping, we’ll see each other in a few days.’

The boy gazed into his eyes for a moment with a curious, enigmatic expression, halfway between affection and pity. He opened the door and walked away.

Artemidorus watched him for a while from the threshold and then, as no one seemed to be around, took a few steps down the hall to see if he could find out what was happening. But as he was about to turn left towards the peristyle, he found one of his guards in front of him.

‘Out for a walk, maestro?’ he said with a jeer. ‘Where do you think you’re going?’

Artemidorus felt a wave of fear and then one of powerless anger. ‘To have a crap,’ he replied.

In via Etrusca vetere, a.d. III Id. Mart., secunda vigilia

The Old Etruscan Trail, 13 March, second guard shift, eleven p.m.

Publius Sextius, hanging one-handed from the branch of a thorn bush, was trying to grab on to a rocky outcrop and failing. He was bleeding from an extremely painful flesh wound and he could feel a warm trickle on his left side. All at once he heard his horse snorting.

‘Here, boy, over this way. . over here,’ he said.

The horse seemed to understand his master’s words. He drew close and pushed his whole head over the brink of the drop. In so doing his reins dangled forward, practically brushing against the hand gripping the thorn bush. Publius braced himself and swung back and forth until he had built up enough momentum to reach the reins with his free hand and grab them.

As soon as the horse felt the sharp tug he became frightened, dug in his rear hoofs and began to back up with all the strength he had. Once he had hauled his heavy load over the rim of the embankment, Publius let go, so that the terrified horse would not drag him off.

He tried to bandage his wound as best he could, then waited for the skittish animal to calm down sufficiently to approach his master again, helped along by the sound of Publius’s voice and a handful of fresh grass in his fist. When the horse was finally within reach, Publius grabbed the reins and leapt on to his back, ready to resume his journey and make up for lost time.

As he was advancing at a good pace under the moonlight, he thought of the strange coincidence that could have cost him his life. How could those four be waiting for him, there in the mansio,as if he’d given them an appointment? He recognized the man in the grey cloak with the weasel’s face from that station on the Via Aemilia where he’d changed his horse several days before. How could he have got ahead of him so easily? He had to have known exactly where he was going.

If someone had been there at that moment, they would have seen a grin forming on Publius Sextius’s face. He was satisfied and triumphant at having solved the mystery. The arm that had so conveniently been used against him — Nebula’s map — could be turned just as easily against them. So, in the same way that the enemy knew where to lie in wait, Publius Sextius knew where he’d be able to ambush his enemy.

The road was becoming wider and the vegetation less thick. More bare-boughed trees, rather than evergreens, let the moonlight filter through.

How much further did he have to go? Publius Sextius wished he could fly, even though his weariness was dragging him down considerably. He didn’t remember when he had last had enough sleep, when he had consumed a normal meal sitting at a table with a jug of wine in front of him. He had been racing, racing against time itself, tiring one horse after another, but never giving up, never stopping to catch his breath. He would make it. He was Publius Sextius, senior front-line centurion, known as ‘the Cane’.

The Eagle is in danger

The message he had to deliver rang through his mind a thousand times each day, each night.

He pulled up, exhausted, at the entrance to an inn on a road with a cluster of rather wretched-looking stone and brick houses encircled by pens full of sheep and goats. The inn doubled as a message station for those travelling on behalf of the state.

The innkeeper was a heavy-set man of about sixty, with thinning hair combed back from his brow. His shoulders were wider than his paunch, a rarity in his line of work.

‘I’m a centurion,’ said Publius, showing him the titulushe wore on his neck. ‘I’m looking for a man who ran off from a mansioback there in the mountain, not only without paying his bill, but relieving a good number of customers of whatever they had in their pockets and the stableman of a good horse. A bloke with a face like a mouse or a weasel, take your pick, a straggly yellow moustache, hair like straw. He wears a grey cloak, day and night. Have you seen him, by any chance?’

The innkeeper nodded. ‘Your man passed through here.’

‘Where is he now?’

‘He’s gone.

‘Gone where?’

The innkeeper hesitated. The information he had received didn’t match what the centurion had just told him.

‘What’s wrong?’ asked Publius Sextius.

‘Seems strange to me that a pickpocket and horse thief like the one you’ve described would have access to a signalling station. That’s where he’s headed, but he’ll be back. I gave him a better horse than the one he was riding and he left me all the money he had as surety.’

Publius Sextius scratched his chin. ‘I know that place. It isn’t far. Bring me a jug of wine, some bread and a piece of cheese. I have to eat something. And give some barley to my horse — he’s earned it.’

The innkeeper served both man and horse promptly, relieved that he wasn’t getting involved in this story, at least not for the time being.

In Monte Appennino, statio Vox in Silentio, a.d. III Id. Mart., secunda vigilia

The Apennine Mountains, the Voice in the Silence station, 13 March, second guard shift, eleven p.m.

The station, perched high on the mountain ridge, was situated in such a way as to receive signals from both west and east. The second guard shift was ending and three men were on duty, two inside and one up in the watchtower. A gusty north wind was blowing and the man posted up there came inside, shivering and stamping his feet on the floor.

‘There’s a priority code coming in,’ he said. ‘The message regards the security of the republic.’

‘What are you talking about?’ asked one of his two comrades.

‘We have to intercept any messengers directed south, especially two men fitted out as speculatores.’

‘What do you mean by “intercept”?’ asked the other.

‘Stop them, I suppose,’ replied the man who had just come in.

‘What if they won’t stop?’

The man drew his finger across his throat in an eloquent gesture and added, ‘How else?’

Mansio ad Vicum, a.d. III Id. Mart., tertia vigilia