‘There, that’s better. Now – I want you meet a guest of mine.’

Nikolaos dusted off his hands as Leo presented Lilla to him, explaining who she was. The man was very tall for a Byzantine, with a smooth dimpled face and long elegant fingers. He bowed self-consciously over her hand. ‘My lady,’ he said, his voice smooth but sonorous. ‘It’s an honour to receive you here.’

‘Tell her what you’re doing.’

‘Yes, of course, sire. We are testing a new syphon this morning.’

‘It seems to be working.’ Leo gave a dry chuckle.

The man stroked nervously at the bridge of his nose. ‘Well – almost, sire. The viscosity is still not quite right.’

‘It’s impressive, nonetheless,’ Lilla offered. ‘Yes. . . And rather horrifying, don’t you think?’ he added, with another nervous pluck at his nose.

‘Isn’t that the point?’

‘Yes. I suppose it is.’ The man’s eyes darted like a bird’s, seeming ill at ease in new company.

‘Go on,’ urged Leo. ‘Tell her how the thing works.’

‘Majesty?’ The fire-maker’s smooth brow crumpled in a frown.

‘Well?’

‘I thought, in light of what you told us two days ago—’

‘What? No! Good God – Queen Lilla is no threat. She’s never even seen an Arab! Go on – explain it to her. Not the detail, man – the principle, the principle!’

‘As you wish, Majesty.’ And so he did, looking decidedly uncomfortable at first, but soon warming to his own expertise and the readiness with which she drank in his every word. It seemed the genius of it was a combination between both the mechanics of the syphon machine and the composition of the liquid itself. But she felt that his explanation left the details deliberately vague.

‘Of course, it’s all rather precise. Any mistakes and. . . well, it doesn’t work.’

‘Fascinating. Still, it must be rather gloomy, working down here, so far from daylight. I feel rather sorry for you.’

‘Nonsense,’ growled Leo. ‘We pay him well enough, I assure you. Besides, it’s his vocation.’

Nikolaos smiled at Lilla. He had a gentle face, pale and sensitive. ‘Your concern is kind, my lady. But the emperor is right. Our father came from Antioch. He lost his lands to the infidel when Syria fell. He never forgot it, nor would he let us forget. I suppose this was his way to take back something of all that he lost.’

‘By burning men to death?’ she said, in a voice innocent as a lamb.

‘By saving an empire!’ Nikolaos blustered. ‘He saved many lives. Saved a way of life.’

‘The city will always honour his name for it,’ said Leo reassuringly.

‘I’m sorry,’ she said. ‘I’ve offended you.’

Nikolaos merely smiled but the wound was plain to see.

‘How can I make it up to you?’

‘There’s no need—’

‘Truly, I must.’

‘Well. . .’ He hesitated, apparently too coy to go on.

‘Please.’