It was not a day for Ballista to be late. Everyone knew what he had done the previous year – turned his hands on a man who, no matter how briefly and how very wrongly, had worn the purple. He had thrown Quietus – may his name be damned – from a tower, a cliff, the pediment of a temple; had stabbed him, strangled him, beaten him to death with a chair leg. In one lurid version, he had torn his heart out on an altar. The details of the execution might vary, but everyone agreed what had happened next. The soldiers had acclaimed Ballista emperor. Certainly, the barbarian had laid down the diadem after just a few days. And certainly, Odenathus, the king of Palmyra, who now oversaw the eastern provinces of the Roman empire in the name of the true emperor Gallienus, had pardoned him. But a man who has killed an emperor, or even an ephemeral pretender, will always be the object of curiosity and some suspicion. Not a man who can afford to be late for a festival of the imperial cult.

It was all rather worse than the idlers in the bars and baths had it. As soon as the deed was done, Ballista had written to the emperor Gallienus: a letter of explanation, a request for clementia, a plea to be allowed to retire into private life, to live quietly in Sicily. The cursus publicus would have taken the letter west at about fifty miles a day. It had been sent months ago. There had been no reply.

As youths, Gallienus and Ballista had both been held at the imperial court as sureties for the good behaviour of their fathers. The young men had got on well. They could even have been counted friends. Ballista had hoped it would help. He had hoped he would be allowed to live quietly as a private citizen, that he would not be convicted of treason. If declared guilty of maiestas, Ballista hoped his property would not be confiscated, that his sons might inherit. If the verdict was bad, he hoped for some form of exile rather than the executioner’s sword. For months, Ballista had hoped all these things, but there had been no reply.

That was not all. Many years ago, Ballista had killed another emperor. Not many people knew of the young Ballista’s role in the death of the terrible Maximinus Thrax. Most, if not all, the other twelve conspirators were dead. Ballista had only told five people. One of them was also dead. Three of the others were still with him: his wife Julia, his freedmen Maximus and Calgacus. But, worryingly enough, the fifth one, his ex-secretary Demetrius, was now in the west; precisely, in the court of Gallienus. It would not be good if a report arrived there that Ballista had been anything other than punctual for a festival of the imperial cult.

With a final, slightly disconcerting flourish, Constans finished the shave. Ballista thanked him, avoiding the eyes of Maximus and Calgacus. On cue, their breakfast arrived. The Jewish slave woman Rebecca put out bread, cheese, soft-boiled eggs, as well as honey, yoghurt and fruit. A substantial ientaculum for a Roman or Greek, nothing too taxing for the three northerners.

‘Tell me, darling girl,’ said Maximus, ‘are you frightened of big snakes?’ He spoke to Rebecca but was looking at Calgacus. She blushed and shook her head. Calgacus ignored him. ‘Sure, you must be getting used to them,’ the Hibernian continued, all wide, blue-eyed innocence. ‘Living here, I mean. I heard tell there was one hereabouts built on such a heroic scale it won applause when its owner took it to the baths. Ugly-looking thing, though, it was.’ Rebecca left as quickly as possible.

‘Bastard,’ said Calgacus.

‘Poor girl,’ said Maximus, ‘ending up with you on top of her.’

Hippothous came in to join them. The snake was gone. They all started eating. The magpie was hopping about in its cage, squawking annoyingly.

‘I hate caged birds,’ said Ballista.

‘You have always been a sensitive soul.’ Maximus nodded. ‘There is a terrible sadness in their singing.’

‘No, it is the smell – bird-droppings, moulting feathers: puts you off your food. I would wring that fucking thing’s neck, if it were not for my wife.’

Breakfast finished, Constans and three other slaves helped the men into their togas. The draping, winding and folding took a long time. The Roman toga was not something you could put on without help and, once arranged, the heavy thing curtailed any sudden, unconsidered movement. No other people wore such a garment. Ballista knew those were three of the reasons the Romans set such store in it.

Eventually, the four citizens were appropriately accoutred: gleaming white wool, deep-green laurel garlands, the flash of gold from Ballista’s mural crown. There was no sign of the women and the children. The magpie had not let up.

‘Tell the domina we will wait for her outside, down on the Sacred Way.’

Outside, a cold pre-dawn, no wind; the stars paling, but the Grapegatherers still shining faintly. There was a hard frost over everything as they walked down the steep steps. Dogs barked in the distance.

The Elephant was no more expensive than the other bars along the Embolos. Nothing was going to be cheap along the Sacred Way. The heavy wooden shutters were open. Hippothous and Calgacus went inside.

The sky was high, pale blue, silvered in the east, streaked by a lone long stretch of cloud, like a straight line carefully drawn. The swallows were high, wheeling and cutting intricate patterns.

‘One day, do you think the sky will fall?’ Maximus asked.

‘I do not know. Maybe.’ Ballista carried on watching the swallows. ‘Not in the way you Celts think it will. Maybe at Raknarok, when everything falls. Not on its own.’

‘Your cousins the Borani and the other Goths, they think it will fall.’

‘Not my cousins. Nothing but ignorant refugees.’

‘And they speak highly of you,’ smiled Maximus.

The others came out with the drinks: four cups of conditum. The ceramic cups were hot to hold. The steam smelt of wine, honey and spices.

‘Calgacus, do you think the sky will fall?’ Maximus asked.

‘Aye, of course. Any day now.’

As a Hellene, Hippothous, unsurprisingly, looked superior.

Ballista regarded his friends. Calgacus, with his great domed skull and thin, peevish mouth. Maximus, the scar where the end of his nose should have been pale against the dark tan of his face. And then there was Hippothous. Things were not the same with him as they had been with Demetrius. Of course, Hippothous was older – most likely about Ballista’s own age. Yet possibly it was more a question of origins. While Demetrius had come to Ballista as a slave, Hippothous had been born a free man – according to his own account, a rich young man that misfortune had turned to banditry or something close to it. It could be the latter was just too new an addition to the familia yet to be a friend. But there was something about Hippothous, something about his eyes. Ballista was far from sure about his new secretary.

The chariot of the sun hauled over the shoulder of the mountain. Up above, the swallows flashed gold and black. Along the Embolos, many of the early risers turned to the east and blew a kiss. A few went further, prostrating themselves in the street in full proskynesis . None in Ballista’s party moved. Each to his own gods, some to none.

‘ Dominus.’

Ballista turned, and there was his wife. Julia looked good. Tall, straight, what the Greeks called deep-bosomed. Her hair and eyes were very black against the white of her matron’s stola.

‘ Domina.’ He greeted her formally. Her black eyes betrayed nothing. Things had not been comfortable between them for a year or so. He had not asked why. And he was not going to. It might be to do with a girl in Cilicia called Roxanne. The unease had appeared after that, after he had come back from Galilee, where he had been sent to kill Jews, when Julia had returned from the imperial palace in Antioch. Someone there might have told her about Ballista in Cilicia, about Roxanne. Things were not comfortable. But the daughter of a senator never made a scene in public, and she did look good. Then there were their sons.

‘ Dominus.’ Isangrim stepped forward respectfully. He was a tall boy, just turned ten. And he was quick. He knew his mother expected a certain formality between father and son, expected him to behave with the dignitas appropriate to the descendant of a long line of senators on her side. But he knew it irritated his father. Having held the dignified pose for a moment, Isangrim grinned. Father and son clasped forearms, as Isangrim had seen Ballista do with Maximus, Calgacus and the other men he had served with. They hugged.

It was all too much for Dernhelm. The three-year-old escaped the hand of Anthia, one of the two maids with Julia. The boy launched himself at his father and brother. Ballista scooped both boys up. He heard a tut of annoyance from his wife. Ignoring it, he swung the boys high, burying his face in the neck of first one then the other, hair flying, all three laughing; deliberately defying her.

As Ballista set his sons down, another small child barrelled into them. Wherever Dernhelm was, Simon, the Jewish boy Ballista had brought back from Galilee, was also likely to be found. They were much of an age; both full of living. Rebecca started forward to retrieve her charge. Ballista smiled and waved her away. He hugged Simon as well. He had been told often enough by his wife that it was a bad idea to treat a slave child as if it were free, to make a pet of it. He knew it was true. He would have to do something soon. Modify his behaviour or manumit the child. Then there was Rebecca herself. She had been purchased down in Galilee to look after Simon. With her, it depended on what Calgacus wanted. Soon Ballista would have to ask him.

The Caledonian himself came forward. ‘Aye, that is it, why not mess up your toga.’ Calgacus often seemed to be under the misapprehension that, if he adopted a muttering inflection, his voice, although pitched at a perfectly audible volume, would not be heard. ‘After all, it is not you that has to sort it out.’ Quite good-naturedly, he shooed the children away.

‘And it is not you either these days.’ Ballista gestured to Constans. The voluminous woollen drapes of the barbarian’s toga rearranged just so, Constans collected Rebecca and Simon and went back up the steps that ran between the blocks of housing that clung to the terraced hillside. Ballista, his wife and two of her maids, his sons, his two freedmen and his accensus set off up the Sacred Way.

The Embolos ran away uphill in front of them, the smooth, white base of a vertiginous ravine of buildings climbing the slopes on either side. Now there was activity along its length. Precariously up ladders, men fixed swags of flowers from pillar to pillar, garlanded the many, many statues. Others were bringing out small, portable altars, readying the incense and wine, kindling the fires. The air already shimmered above some of them.

All the Ephesians were taking pains over this festival, none more so than the members of the Boule. The four hundred and fifty or so rich men who served on the city council had paid for the flowers that festooned all the streets and porticos. They had paid for the frankincense and wine the ordinary citizens would offer as the procession passed, and the much greater quantities of wine they would drink when it was gone. It had cost a great deal – Ephesus was a large and populous city. Yet it might prove worth every obol. The city had been on the wrong side in the latest civil war. The year before, it had supported Macrianus and Quietus against Gallienus. Of course, it had had no real choice. But that had not always helped in similar circumstances when the winner was feeling vengeful, or simply short of funds. If imperial displeasure fell on the city, it would fall on the members of the Boule. Rich and prominent, serving for life, there was no way they could escape notice.

No one had more reason to be generous than the current asiarch in charge of the day’s festival. As high priest of the imperial cult in Ephesus, the metropolis of the province of Asia, Gaius Valerius Festus could not be more prominent. He was one of the very richest men in the city. Recently, he had pledged a fortune to dredge the harbour. He had been one of those whose homes had been deemed palatial enough to entertain the pretender Macrianus and his father when they travelled through on their way to the west to meet their fate. To add to his sensitivity, his brother was a Christian. The deviant brother had disappeared from jail and had been in hiding abroad for more than two years. He had reappeared shortly after the fall of Quietus. The emperor Gallienus was known to be extraordinarily relaxed about such things, but the family reunion had caused no great pleasure in the soul of the asiarch. It was no wonder Gaius Valerius Festus had invested a huge sum in the festival: choirs, musicians, several leading sophists – and the gods knew they did not come cheap – and a whole herd of oxen to be sacrificed and provide a roast meal for everyone in the city.