Aleksei looked at the creature. It was absurd to trust a vampire, but if they were not to be trusted then it would be foolhardy to stay. Their hatred of Iuda seemed genuine enough, and that would make their actions over the next few hours pleasingly predictable.

Aleksei nodded. ‘Thank you,’ he said, then turned and ran back up the tunnel which he had descended scarcely an hour before.

‘Thank you!’ he heard called from behind him, but he did not stop to look back. He didn’t stop to check the tiny scratch marks he’d left to guide his way out; instinct told him the correct path.

Only when he saw the light of day streaming in through the end of the tunnel and finally made it outside – pressing himself against the cliff face to avoid falling from the narrow ledge – did he stop, and take in huge, grateful lungfuls of the cool, fresh Crimean air.

THE ROYAL PARTY HAD LEFT THE CITADEL BY THE TIME ALEKSEI returned to it. It was the right thing to do – Wylie might have been tempted to stay and wait for Aleksei to emerge from the caves, but his duty was to ensure that the tsar got safely away.

They were almost halfway back to Bakhchisaray when Aleksei caught up with them. They had stopped and dismounted at the Uspensky Monastery, which they had passed by on the way up to Chufut Kalye. The previous day the tsar had attended a Mohammedan ceremony in the khan’s palace. Earlier today he had been taking tea with Jews, and now he was going to visit an Orthodox chapel. It was not a reflection of the make-up of his nation as a whole, but the Crimea had had too many masters over the years to settle upon any one god.

The most remarkable thing Aleksei observed was the dutiful calmness with which Aleksandr was continuing his activities. He asked the usual, polite questions of the priests and the monks, and showed great interest in the architecture. Like so much in the area, the monastery was built into natural caves in the rockface. For a moment, Aleksei feared there might be some subterranean path back to Iuda’s lair, but it was unlikely. They were on the other side of the valley from Chufut Kalye, and any tunnel would have had to go around it, or underneath it. It was at that moment that the tsar first caught sight of Aleksei, across the open courtyard. Only a raised eyebrow indicated he had any recollection of the events they had both witnessed that day.

Wylie caught up with him as they were all treated to an impromptu lecture on the history of the building from one of the older priests.

‘You’re all right then, I see,’ he said.

‘Nothing broken,’ said Aleksei.

‘You can imagine my relief when His Majesty returned.’

‘How is he?’

‘He seems perfectly well; a little distracted perhaps. He won’t tell me anything of what happened.’

‘Did he explain his absence?’ asked Aleksei.

‘He just said he’d gone exploring and complained that Colonel Salomka had panicked.’

‘I suppose he wasn’t down there for very long.’

‘You met Cain?’ asked the doctor.

Aleksei nodded.

‘What happened?’

‘Some of his experiments got a little out of hand.’

‘You mean…?’ gasped Wylie.

The priest had taken them to a long flight of steps that led up to the chapel itself. He had begun to ascend. Aleksandr was just behind him, followed by Tarasov and Salomka. Aleksei and Wylie were next.

‘I don’t think Richard Cain will be making any more presentations to the Royal Society. Even so, I’d very much like for us all to be off these damned mountains before nightfall.’

‘Of course,’ said Wylie. ‘Did His Majesty witness any of this?’

‘No, I sent him away almost…’

In front of them, Tarasov and Salomka suddenly rushed forward. The priest turned back to see what the commotion was. Aleksandr had collapsed. Tarasov loosened his collar and Wylie dashed forward with a bottle of sal volatile, which he waved under the tsar’s nose. Aleksei felt his own approach was a little more practical. From his pocket he fetched a small flask of brandy, from which the tsar took a grateful sip. The whole incident was over in moments, and the tsar was back on his feet before any but those in the closest proximity to him could even notice what had happened.

‘I really must apologize, gentlemen,’ he said, continuing his climb of the stairs, but stopping almost immediately to catch his breath. ‘I have overstretched myself a little.’

Wylie glanced at Aleksei. ‘A delayed shock, you think?’

‘It’s only to be expected.’ Aleksei thought for a moment. ‘Perhaps it will do us a favour – persuade the tsar to return sooner.’

‘Let’s hope,’ said the Scotsman.

But as the others moved on, Aleksei paused for a moment, standing on the steps at the point where Aleksandr had fainted. Just ahead of him, at the top of the stairway, was a small gatehouse, and to the left of the gate he saw what Aleksandr must also have seen. It was a ubiquitous sight in Moscow, but it was not uncommon elsewhere in Russia either. Only recently, Aleksei had been considering its echoes in a statue in Petersburg. But this was the first time he had suspected that the image might mean to Tsar Aleksandr something akin to what it meant to Aleksei himself.

It was an icon; an icon of a saint on horseback driving a spear into the mouth of a monster. An icon of Saint George and the dragon.

After his collapse, the tsar most certainly did appear to take a more cursory interest in the sights before him. After the monastery they directly began their journey back to Bakhchisaray, with only a few farewell waves to the local people hindering them in any way.

Once they were back down in the river valley that would lead them to the town, Aleksei and Wylie rode side by side in discussion. Aleksei briefly described what had happened. He did not mention his previous meeting with Cain, under a different name. Wylie shared Aleksei’s ambivalence as to how the problem had been resolved. In the end he concurred with Aleksei’s decision – or at least said he did. For him, hatred of the voordalak was not as entrenched as it was in Aleksei, but neither had he seen for himself the piteous specimens in those caves. So though he might have weighed the two sides of the argument differently, in the end he came to the same conclusion. What was most important, they both agreed, was that it was Cain who had been the main threat to the tsar and that he was a threat no longer. Aleksei felt more relaxed than he had riding out along the same road that morning.

As might be expected from a man of science, Wylie showed a keen interest in what Iuda had been trying to discover, if not in his methods. When Aleksei mentioned Raisa Styepanovna and her absent reflection, Wylie began to describe one of the experiments from the notebook.

‘As you said,’ he explained to Aleksei, ‘it seems very selective in terms of what can be seen and what cannot. Why can’t you see their clothes, for example? And in the end you’re right, an intelligent selection is being made – the interesting question is, by whom?’

‘How do you mean?’

‘Well, Cain’s thought is – was – that it’s the mind of the viewer that blocks out the image of the vampire. So you do actually see the creature, in terms of the light falling into your eyes, but your brain blots it out. For what reason, he couldn’t tell. The point is, the viewer’s brain isn’t going to be so stupid as to just remove the vampire and leave its clothes standing there empty, or indeed the chain stretching out in the case you described. The brain is trying to protect the viewer in some way, so it presents a coherent picture of the scene – sans vampire.’

‘But how could he test that?’ asked Aleksei.

‘Well, first he thought he’d do it by having people who didn’t know that the creature they were seeing was a vampire look at one in a mirror. If they didn’t know it was a vampire, then why should the brain block it out?’