They were arriving at the basilica. In the late-afternoon sunlight, the building was bathed pink on its western side; its eastern half swathed in shadow. The lines and curves of its dome and buttresses all formed a beautiful whole – symmetrical and satisfying to the eye.

And yet something about it made Erlan shudder.

Elsewhere in the palace, a very different conversation was taking place.

‘You told me to keep my eyes and ears open.’

‘I had assumed that’s why you’re here,’ returned Katāros.

‘You said if ever I did you a service, you would make it worth my while.’

‘Have I not been paying you all this time?’

‘Some. I want more.’

‘First tell me what you have for me.’

‘No. First I name my price. You accept. Then I tell you.’

‘For a slave, you are exceptionally impertinent,’ he said wearily. ‘Name your price then.’

‘Fifteen solidi.’

‘Fifteen? Not twenty? Not fifty?’

‘Fifteen is fair. And my freedom.’

Fifteen was a pitifully small sum for a betrayal. But doubtless more money than this wretch could dream of handling in her lifetime. ‘Agreed, then. Now speak up.’

The slave-girl smiled, a most unpleasant sight. ‘You’re in danger.’

‘What sort of danger?’

‘You’re to be denounced. My mistress knows what you are. I know what you are.’ The same chapped lips and stained teeth mouthed the word ‘traitor’. Despite his calm exterior, a shiver of dread rippled down his spine.

‘Why should I trust your word? You betray your mistress easily enough.’

‘You’d be a fool if you didn’t. But it’s your neck. Suit yourself.’ Yana held out a grubby palm. ‘Fifteen solidi.’

The eunuch’s mind was working, different thoughts flaring in different languages. . .

The girl was still holding out her hand. ‘Come on. Fifteen solidi, you said.’

‘Fifteen, yes. . . How would you like to double it?’

Domnicus reached up with his taper to light the last of the three candles standing on the altar. The air was already heavy with incense and the musky silks of his black robes. But apart from him, and Lilla and Gerutha, the church was empty, and the gathering gloom of evening held sway over all but one of the eight apses that formed the great marble circle.

Domnicus had fallen in with their plan willingly enough. As priest to the imperial family, he was uniquely placed to help them. But it wasn’t his office alone that made him want to protect the emperor. ‘The hand of God is on that man,’ he had told them, the conviction in his eyes leaving little room to contradict him. ‘His rise to the throne makes no sense unless the Lord wanted him there. He’s been a man of violence all his life. A soldier and a general. But the path opened up ahead of him like the parting of the Red Sea. He is the right man for this time. The chosen man.’