‘Brutus’s mother?’

‘Yes. Brutus’s mother, Cato’s sister, Caesar’s long-time mistress. Perhaps still his mistress now.’

‘Why would she talk to me?’

‘There’s no saying she will, but she’d have good reason to do so. She may very well want to prevent the worst from happening. Look, Servilia has already lost Cato, who preferred death over Caesar’s pardon after he’d been defeated in the African campaign. If Caesar were to be killed, Servilia would lose the only man she’d genuinely loved in her whole life. If he were to be saved, she would probably lose her son, assuming Brutus is implicated in the plot. So in either case she would be interested in averting the threat, no matter where it’s coming from or at whom it’s directed. On the other hand, we can’t imagine that she would warn Caesar personally if she did know something, because doing so would put her son’s life at risk, if what we’re thinking turns out to be true. There are some that say that Caesar spared Brutus after the Battle of Pharsalus because he didn’t want Servilia to be hurt.’

Silius raised his hands to his temples. ‘This is. . a labyrinth! How can I hope to make my way through such a tangle of conflicting motives? I’m just a soldier.’

‘You’re right,’ replied Antistius. ‘Better not to get mixed up in it.’

‘You,’ continued Silius, ‘how do you know so many things?’

‘I don’t “know”. I make assumptions, reflect on them, draw my own conclusions. And then I’m a doctor, don’t forget that. Any doctor who’s worth the name has to strive to understand what isn’t explained, to see what’s hidden, to hear what hasn’t been said. A doctor is accustomed to fending off death. And what I think is that Servilia — if she’s privy to what’s happening, that is — has only one option. To approach the person she holds dearest and point them in the right direction. And only she knows exactly what that might be.’

‘But if you wanted to help Caesar, what would you do now?’ asked Silius after another long pause.

‘I have already taken certain initiatives,’ replied Antistius enigmatically.

‘So why haven’t you told me? What were you waiting for?’

‘For you to ask me.’

‘I’m asking you now. Please. You know you can trust me.’

‘I know. And I would never tell anyone else what I’m about to tell you.’

Silius leaned in closer and awaited Antistius’s revelation in silence.

Eventually the doctor began, speaking slowly and clearly: ‘Brutus has a Greek teacher. .’

Silius widened his eyes.

‘His name is Artemidorus. I cured him of an ugly case of vitiligo. You know how much the Greeks care about their looks. .’

Silius smiled, thinking of all the attention Antistius devoted to his own personal appearance.

‘I believe he is grateful to me. I’ve never told him how I do it and every once in a while he calls on me to repeat the miracle. So, you see, I have considerable power over him. I’m trying to get information from him, although I’ve acted very carefully. I don’t want to jeopardize everything. I know what you’re about to tell me: that there’s no saying we have the time, but that’s a risk I’m ready to take. I don’t have any alternative, at least not for the moment.’

Silius thought of the centurion Caesar had sent north on a mysterious mission. Publius Sextius was the one person he would have liked to talk to at this moment of such anxiety and uncertainty. It was some consolation to think that Caesar would certainly never have allowed him to go if he had felt there was any immediate danger. Or maybe he’d sent him away because he couldn’t stand the waiting any more and wanted to face his destiny. Whatever destiny that might be. There was no definite answer, no obvious solution.

At length Silius got to his feet and thanked Antistius for his time. ‘I realize that it may have sounded as if I was ranting, but I needed to talk about this with someone I trust. I feel better now.’

‘I’m glad you did,’ replied Antistius. ‘Come whenever you like. I’d rather it was here than at the Domus Publica. If I can give you some advice, don’t take any initiative on your own without consulting me. And don’t torture yourself. Remember that we know nothing for certain and may well be worrying for no reason. All Caesar said was that he’d heard strange rumours, after all. Such a vague expression.’

‘All right,’ said Silius. ‘I’ll do as you suggest.’

As he left, crossing the square in front of the Temple of Aesculapius, he could see the standard of the Ninth Legion flying from the island’s main building. So Marcus Aemilius Lepidus was present with his soldiers. Only a madman would risk taking any kind of action with an entire cohort quartered in the heart of Rome and the rest of the legion camped just outside her gates.

Romae, in Domo Publica, a.d. VIII Id. Mart., hora octava

Rome, the residence of the Pontifex Maximus, 8 March, one p.m.

Silius went directly into the kitchen to check that Caesar’s lunch was ready. The usual: flatbread with olive oil, mixed sheep’s and cow’s milk cheese, a few slices of Gallic ham from Cremona, the boiled eggs and crushed salt that he invariably requested, and a plate of freshly picked bitter greens. Silius lifted up the tray and took it into the study.

‘Where were you?’ Caesar asked as soon as Silius walked in.

‘On the island, commander. Antistius wanted to know how you were feeling.’

‘And what did you tell him?’

‘That you were quite well and were working.’

‘That’s almost true. Eat something yourself,’ he added. ‘All this is too much for me. Have you seen my wife?’

‘No. I’ve just come from the kitchen.’

‘She left shortly after you did and hasn’t returned. She’s just not the same any more. She seems so. . I don’t know, restless.’

Caesar began to eat, sipping now and then from a glass of the Retico wine which one of his officers, stationed at the foot of the eastern Alps, regularly sent him. He mentioned a shooting pain that an old wound on his left side was causing: a sign that the weather wasn’t quite settled and that sooner or later it would begin to rain again or worse. Silius cut the flatbread and ate some with an egg and a little salt. He agreed that the weather could certainly be better given the season, with springtime just around the corner, and it was evident to both of them that their conversation was a thousand miles away from their thoughts.

All at once Caesar wiped his lips with a napkin and said, ‘While you were at the island a message from Publius Sextius arrived.’

Mutatio ad Medias, a.d. VIII Id. Mart., hora decima

The Medias changing station, 8 March, three p.m.

The fields stretching south of the Po flew by under the hoofs of Publius Sextius’s horse as he raced down the road that unwound like a grey ribbon through the green meadows at the foot of the Apennines. The fog had dissipated and the sun shone in a clear, cold sky, its light reflecting off the snow which still covered the mountain peaks.

The swift Hispanic steed, his coat shining with sweat, was showing signs of fatigue, but Publius Sextius continued to push him on nonetheless, snapping the ends of the reins against the horse’s neck and urging him continually forward with words of encouragement.

The rest station, a low brick building with a red-tile roof, was coming into sight now. It stood near a little stream, surrounded by bare hawthorn bushes and flanked by two ancient pine trees. He slowed the horse to a walk and entered the main gate, a stone archway with a sculpted sun at its keystone. The small porticoed courtyard inside had a little fountain at its centre that poured water into a drinking trough carved from a boulder.

Publius Sextius jumped to the ground, took the copper ladle at the end of a chain and drank in long draughts, then let the horse slake his thirst as well, a little at a time so he wouldn’t catch a chill, clammy as he was with sweat. He untied a blanket from behind the saddle and covered the horse’s rump. Then he went towards a side door that led to the office of the station attendant. The man stood at the sound of his knock and let him in.