Castus tightened his jaw at the implication, anger rising in his throat; he was satisfied to see the envoy flinch instinctively and step back.
‘Forgive me,’ Marcellinus said, inclining his head as if in apology. ‘But it’s reassuring to know I’m not alone in my suspicions. It seems I must go and talk to Strabo, man to man, and ask him to explain himself. I would like you to accompany me.’
‘Why?’
‘Because I want the meeting to appear more official than merely personal, perhaps. And because what he tells us might be of great importance once we travel into the north. Will you come with me?’
It was more an order than a request, but Castus nodded. ‘Should I arm myself first?’
‘I don’t think that will be necessary. Hopefully we won’t need to murder him.’
They crossed the street from the compound and entered the house opposite. There were two storeys, built around a little pillared courtyard; Marcellinus tossed his cloak to a slave in the entrance hall and then led Castus up the stairs to a door at the end of the corridor. He knocked and waited until they heard the voice of Strabo from inside.
‘Gentlemen, come in,’ the secretary said. He looked flustered, and quickly dusted the knees of his breeches, as if he had just been kneeling. ‘Can I offer you some wine, perhaps?’
‘No thanks,’ Marcellinus replied. He seated himself on a stool by the window. Castus leaned back against the door.
‘In what capacity were you sent on this assignment?’ the envoy asked, hard and direct. Strabo raised an eyebrow, then he sat down on a divan piled with bedding.
‘As the governor’s representative, of course…’
‘A position of great trust for a mere secretary, no? Tell me plainly, Strabo. What is your rank and station?’
As he watched, Castus saw a swift change come over the secretary: the baffled act fell away, and instead he appeared suddenly more controlled and focused.
‘You tell me, envoy. Since you seem to have your suspicions already.’
Marcellinus smiled. He turned to address Castus now. ‘Centurion,’ he said, ‘have you ever heard of the agentes in rebus?’
‘No,’ Castus replied, shrugging against the door. The title sounded so bland it could mean anything, or nothing.
‘They’re a corps of imperial messengers and investigators. They operate in great secrecy, and take their orders from the Office of Notaries and the emperor himself. One of their agents is placed in every provincial governor’s staff.’
‘Spies, you mean?’ Castus pushed himself away from the door with his shoulders. The top of his head brushed the low ceiling. Strabo was smiling to himself.
‘Not spies exactly, no,’ the secretary said. ‘But your guess is correct, envoy. I am an imperial agent, as you suspect. I was despatched eighteen months ago from the court in Treveris to investigate the loyalties of Aurelius Arpagius, governor of this province. Now I have been ordered to accompany you and… make sure everything proceeds in accordance with the emperor’s wishes.’
‘So why did you go to that house in town last night?’ Castus demanded. He had taken a step forward as he spoke. Marcellinus frowned, raising a calming hand.
‘So it was you that followed me?’ Strabo said. ‘I thought somebody did. But I guessed you would send one of your men, or a slave, rather than do it yourself.’
‘Where did he go?’ Marcellinus asked abruptly, confused. ‘What is this?’
‘He went to a house – I don’t know why. There were symbols scratched on the door. Something like a ship, and a sun-wheel thing. An X with a line through it.’
Marcellinus paused, still frowning. Then he suddenly threw back his head and laughed. ‘Oh, wonderful!’ he cried.
‘What I do, or believe, is none of your concern,’ Strabo said quietly. ‘My loyalties to the emperors are beyond question.’
‘I don’t understand,’ Castus said.
Marcellinus was grinning, teeth clenched. ‘Those were Christian symbols,’ he said. ‘Our friend Strabo is the follower of an illicit superstition!’
‘Such a term proves your ignorance,’ Strabo said, with more anger than his expression suggested. ‘My faith is sincere, as are my loyalties!’
Castus knew little about Christianity. It was a secret religious cult, and its followers denied the gods and the authority of the emperors, and went into tombs to worship the ghosts of executed criminals and eat the flesh of the dead. More importantly, it was illegal. Shortly before the Persian war there had been an order discharging Christians from the legions without honour. Then, a few years later, an imperial edict had outlawed the practices of the cult entirely. But in the military fortresses of the Danube there had been little visible sign of it. Could there really be Christians in Coria? Castus felt a cold churning in his stomach. Such men were clearly deluded idiots, but possibly they were also traitorous, even dangerous. Being in the same room with one now was alarming.
‘To be frank, I’m not too concerned about your faith,’ Marcellinus said. ‘You can believe whatever sordid fantasies you wish. Just keep it to yourself. I trust the centurion here is a tolerant man?’
Castus just grunted. He could only speak for himself, but he worried about the effect on his men if they found out.
‘I’m not afraid of you,’ Strabo said with a cool tone. ‘Believe me, I’ve suffered more for the truth than you can know. But our Augustus Constantius is also a tolerant man, and has shown an inspired lack of the persecuting fervour so common in his imperial colleagues.’
‘So he sent you here, out of the way? Very convenient for everyone. I had believed that the imperial service was purged of all your fellow cultists… But no matter. Now everything’s out in the open. Or is there more you’d like to disclose?’
‘No, nothing more. But, as for my role – we all have our orders. Just like you, envoy. And you, centurion. My own orders require me to keep silent on many matters. I hope you can respect that, as you respect the emperor I am glad to serve.’
‘Very well,’ Marcellinus said, standing up. ‘I’m glad we understand each other, Agent Strabo.’
They reached the Wall of Hadrian at dawn the next day. It was misty, and the fortifications appeared suddenly ahead of them, a hard pale line of stone in all that empty grey. As they drew closer, Castus could make out the huts and sheds lining the road that led up to the single gate. The smell of cooking fires too – neither he nor his men had breakfasted yet, and his guts tightened.
Marcellinus rode forward and spoke to the decurion of the cavalry detachment on guard, while Castus and his men stood and stamped in the damp morning chill. Then the gates swung open, and they moved on along the road into the borderland beyond.
There was no change, at first, in the landscape. Fields to either side, and small farms or homesteads. All this country, Castus knew, had been part of the empire once. Now the tribes of the border were Roman allies, settled and peaceable – or so Marcellinus had claimed. He said that they would meet a party of these tribesmen a day or two further north, who would accompany them to the Pictish chiefs’ meeting. Castus was wary of that idea – far better to keep themselves apart from the locals, he thought. Nobody outside the bounds of Roman control could be trusted. But Marcellinus understood their ways, and they would all have to trust in that understanding now. Castus would also have to trust in the interpreter that Marcellinus had hired at Coria, a weaselly Briton with a nervous twitch, named Caccumattus. The little man claimed to be of the Textoverdi tribe, and to speak the language of the Picts fluently, but his Latin was poor enough for Castus to be dubious of his value.
It was a hard day’s march. The road ran straight as ever, but the horizons rose on either side to bare brown hills, craggy with rock outcrops. The farmland fell away behind them, and they climbed across windy uplands with the sky huge and tumbling with clouds above. At the day’s end they reached the outpost fort of Bremenium, a white-walled bastion on the edge of nowhere. The garrison was made up of frontier scouts, tough wiry men on native ponies, most of them Britons from the mountains in the west of the province. Six of them were ordered by their commander to join the envoy’s party – they would act as forward scouts and guides on the roads ahead.