‘I’m sorry, but I don’t see why it’s such a concern.’

‘Because of the mention of blood. There is a disease – if I may call it that – which we know full well is carried in the blood; one with which the tsar has recently come into close contact.’

‘And from which he is suffering no symptoms. Believe me, I would know.’ Even as he spoke, Aleksei wondered if he was being overconfident.

‘I’m not suggesting he is, but I think he may be concerned that he is. Did you hear any of what he and Cain were discussing?’

‘They were speaking English most of the time. The only thing I heard in French suggested that Cain was about to kill His Majesty. That’s when I intervened.’

‘So before that, Cain could have said something that put this idea into the tsar’s head.’

Aleksei shrugged. ‘Possibly, but I think it will be out of his head again pretty soon. He’s not one to perceive illness where there’s nothing there, is he?’

‘Quite the reverse, I would say,’ replied Wylie. ‘Even so, I shall mention my fears to Tarasov.’

‘Will he believe you?’

‘I won’t convey to him the unusual facts we know unless it is absolutely necessary. But if it does prove necessary, I think I’ll find it just as easy to convince him as you did me; and by the same method.’

Aleksei considered for a moment whether to protest at the cruelty of this approach now that they understood the physical pain that would be caused to the voordalak who had donated his skin in the book’s manufacture, but he realized that that was not the true nature of his objection. What he really didn’t like was the way control of events was suddenly being taken out of his hands. He was the expert on vampires, and if consultation were needed with a second doctor, then he should seek it.

But he knew his place. The man he was talking to was personal physician to the tsar. It was a more influential role than that of some secret policeman, however much he might have assisted His Majesty.

And what did he care? If the tsar believed himself to be a chicken, a chimpanzee or a Chinaman, it would be a problem for Russia, but not one that was Aleksei’s responsibility. If he thought himself to be a voordalak then, again, it was nothing to do with Aleksei. Aleksei’s duty lay in dealing with the monsters of reality, not of the mind. And there his duty had been fulfilled.

Aleksei saw for himself the tsar’s preoccupation a few days later. They had quit the Crimea and were now only a few days from Taganrog. The party had stopped for lunch and all of its more senior members – colonels included – were sitting at the same table. It was Aleksandr himself who raised the issue.

‘You recall that demonstration of the effectiveness of quinine that Dr Lee showed us,’ he said, addressing his words to Wylie.

‘I recall it,’ replied the doctor, though Aleksei suspected a note of caution concerning the subject that the tsar might be turning to.

‘Well, I have heard that one of the limitations of the substance is that it tastes so foul. Patients simply will not drink it.’

‘It’s not exactly foul, Your Majesty, merely bitter. The flavour can be disguised, but even on its own it is not unpalatable.’

‘I find that very hard to believe,’ responded the tsar. ‘Let’s find out. Do you have any?’

Wylie exchanged a glance with Tarasov, and the latter left the table and went out of the room. Aleksei watched him out of the window, going through one of the bags strapped to the back of his carriage. He returned moments later carrying a jar containing a white powder. The tsar opened it up and, having licked his finger, dabbed it in and put a little of the substance on his tongue.

He pulled a grimace, like some child who had encountered a new and harsh flavour – obviously exaggerated – and all round the table laughed. After he had flamboyantly recovered himself, he spoke to Tarasov.

‘You and Wylie certainly don’t go out of your way to spoil patients with pleasant-tasting medicines.’

Again there was laughter at the table and when it subsided the conversation moved on elsewhere, but Aleksei noticed – as he suspected did both Wylie and Tarasov – that the tsar never returned the jar of quinine.

Aleksei had grown a little saddle-sore after two weeks on the road. There was a spare coach, which on the way out had been packed with provisions that had now dwindled to almost nothing, and so he chose to journey on in there for a little while. He had quickly found it to be, if anything, less comfortable than riding on horseback. On these uneven roads, at least a horse had the ability to pick its way between the potholes.

It was early evening before they changed horses. Soon after they had stopped, Aleksei’s slumbers were interrupted as first Wylie and then Tarasov clambered into the carriage.

‘Look at this,’ said Tarasov. He held out what appeared to be the jar of quinine.

‘So His Majesty returned it to you,’ replied Aleksei. ‘Good.’

‘But look how much is missing,’ insisted Tarasov. ‘He’s taken five or six doses.’

‘Is that dangerous?’

‘Probably not,’ said Wylie, still with the same urgency that his colleague had conveyed. ‘If he’s got any sense he’ll have kept them for later use rather than take them all together. The point is his state of mind.’

‘You still think he believes he…’ Aleksei glanced at Tarasov ‘… has malaria?’

‘Don’t worry,’ said Wylie. ‘I’ve explained everything to Dr Tarasov.’

‘Even so,’ persisted Aleksei, ‘it could just be malaria.’

‘It could,’ replied Wylie, ‘except for this.’ He took out the notebook he had been carrying under his arm. He glanced at Tarasov, who pulled down the blinds on his side of the carriage. Aleksei did the same on the other side. It was probably dark enough for the skin not to be damaged, but privacy was also an issue. Wylie unwrapped the paper and flicked through the book, quickly finding the page he wanted. He held it open under Aleksei’s nose.

‘Look,’ he said. ‘Look at that.’

Aleksei shrugged, reminding Wylie of his lack of understanding of English.

‘Oh, I’m sorry,’ said Wylie. ‘I’ll summarize for you. It’s a section describing how this affliction – vampirism, if you will – may be transmitted from one individual to another. Apparently blood must be exchanged, each consuming the other’s, and then death must follow within a certain time period for the full transformation to take place. Otherwise the effect of the blood expires.’

‘That much I worked out for myself,’ said Aleksei, not mentioning that he also knew it from experience. ‘Cain couldn’t determine what that period was though.’

‘No, but he does say this: “Perhaps unsurprisingly, this period can be substantially shortened if the subject of the potential induction” – that’s the word he uses for it throughout – “if the subject of the potential induction consumes a standard dose of quinine at regular intervals during this period. I would conjecture that the effect works by the same mechanism as does the similar action of quinine on malaria, but I have not yet considered how to verify this.”’

Wylie looked at Aleksei, and the latter could not help but accept that there might be some connection.

‘You haven’t shown His Majesty this, have you?’ he asked.

‘No, but I’m wondering if Cain might not have told him the same information – or if he might have got it from elsewhere. He clearly knows more than he’s saying.’

‘It’s been four days since he was with Cain,’ said Aleksei. ‘You’d think he might have acted sooner.’

‘Perhaps he did,’ said Tarasov. ‘There was another bottle missing from my case. I noticed it a couple of days ago, but I didn’t make the connection until now.’

‘But it’s inconceivable,’ said Wylie, ‘that he would actually imbibe any of the blood of these monstrous creatures.’

‘He drank some wine!’ said Aleksei in an excited whisper. ‘Cain must have given it to him.’