They walked through the palace and out the other side. Wylie turned left and Aleksei followed. Within a few minutes they were at a lodging house. Wylie went in and led Aleksei up to his room. He closed the curtains, checking for any cracks, and lit a candle.

‘Will it be safe here?’ he asked.

Aleksei nodded. He laid the book down on the table and removed the paper. Three familiar words stared up at them.

Nullius in Verba

‘Ah!’ said Wylie. ‘Truer words were never spoken.’

‘You’ve seen them before?’

‘Of course. It’s the motto of the Royal Society.’ Aleksei looked blank. ‘In London. It’s a scientific society.’

‘I read it as “Take nobody’s word for it,”’ said Aleksei.

‘That’s about right. It’s from Horace. “Nullius addictus iurare in verba magistri.”’ Aleksei tried to translate, but Wylie already knew the meaning. ‘“I am not bound to believe in the word of any teacher.”’

‘It’s big, is it, this Royal Society?’ asked Aleksei.

Wylie looked at him, unbelieving. ‘It’s the foremost scientific organization in the world.’ The doctor caressed the book’s binding. ‘Do you know what this substance is?’ he asked. ‘Have you thought of its medical applications?’

‘I have an idea – and I don’t think it will heal anybody. But judge for yourself; read the book.’

Wylie opened the cover and his eyes fell upon the author’s name.

Richard L. Cain F.R.S.

‘Aha!’ said Wylie. ‘The gentleman you asked after yesterday, and a fellow, no less.’ Wylie had dropped into English for that one word.

‘“Fellow?”’ asked Aleksei.

Wylie translated the word into French and then Russian. ‘That’s what the “F.R.S.” stands for,’ he explained, ‘Fellow of the Royal Society. That makes it more surprising that I’ve not heard of him.’

‘It may not be true,’ observed Aleksei.

‘Good point. Good point,’ agreed Wylie. ‘Nullius in Verba, eh?’ He turned his attention to the first full page of text and began to read. His face quickly grew grave. He let out a few exclamations, some in Russian, some in English. He turned the page, but rather than reading, looked up at Aleksei. His face was flushed.

‘This is quite extraordinary,’ he said. He sat down and mopped his face with a handkerchief. His eyes glanced around the room, before falling on Aleksei again. ‘Fiction, of course,’ he added. It sounded like a plea.

‘You saw what happened to the cover.’

Wylie looked up at Aleksei, then back to the book, weighing the evidence of his eyes against the prudence of his years.

‘You must let me read this,’ he said. ‘It will take time.’

Aleksei considered. He was loath to let the book out of his sight, and yet there was nothing more he could get from it without Wylie’s help.

‘Very well,’ he said at length.

‘I’ll call on you when I’m done. I presume Volkonsky has your address.’

Aleksei nodded. ‘I’ll see you soon then.’

‘Very,’ replied the doctor, shaking his hand.

Aleksei went back out into the street. As he set off home, he glanced up to the window above. Dr Wylie stood there holding the book out in the sunlight. A wisp of smoke rose from it, and Aleksei was sure he perceived that scent of burning hair, even though he was too far away. Wylie rapidly popped his head back inside, taking the book with him.

Had he suspected some trick from Aleksei? Or had he simply been unable to believe so strange an observation? Either way, he must now be convinced. That was all Aleksei needed him to be.

Aleksei sat in his rooms all day Sunday, even missing church. Dr Wylie did not come.

On Monday morning, Aleksei heard feet on the stairs. He leapt upright, then sat back down, feigning nonchalance. He had little reason to suppose that whoever it was was coming to pay a call on him, and moreover, the footsteps were far too heavy to be those of Dr Wylie.

The knock at his door was firm.

‘Come,’ said Aleksei.

It was Prince Volkonsky.

‘His Majesty wishes to see you,’ he said, without any preamble, ‘at four o’clock this afternoon. Are you available?’

‘Absolutely,’ said Aleksei. ‘I’ll be there.’

Volkonsky left without another word. Aleksei stood at his window and watched the prince stride powerfully down the street. He was a bigger man in many ways than his brother-in-law (and distant cousin) Sergei Grigorovich Volkonsky. How would the one, the tsar’s right-hand man, react to the treachery of the other, he wondered. He hoped there would never be an occasion to find out. It was still his plan that the whole conspiracy should simply drain away, like rainfall on one of those well-engineered Parisian streets. Once he had dealt with this affair, he would return to trying to effect that hope with new vigour.

What though was the reason for the tsar’s summons? He had said he might call on Aleksei, but there had been no indication it would be so soon. Had Wylie spoken to him? It seemed unlikely. To approach an emperor with a story such as that told in Cain’s notebook would take planning and caution. Had Wylie simply denounced Aleksei as a lunatic? It did not seem to be in the Scotsman’s nature.

He looked at his watch. It was only eleven thirty. Time would tell.

Aleksei arrived at the palace promptly, and was quickly escorted by Volkonsky to the tsar’s personal quarters. Aleksandr was alone – there was certainly no sign of Wylie. Even Volkonsky retired after exchanging but a few words.

‘Sit down, Colonel Danilov,’ said Aleksandr.

Aleksei sat. There was no offer of tea today.

‘The last time we spoke,’ continued the tsar, ‘you asked me why I had come to Taganrog. I’m afraid I did not give you a complete answer.’

Aleksei feigned surprise.

‘You’re not in a position to patronize me, Colonel,’ snapped the tsar, but there was a curl to his lip that Aleksei found infectious. The mood lightened. ‘Nor am I in a position to deceive you, it would seem,’ he added.

‘So, why did you come?’

The tsar handed Aleksei a single sheet of paper, folded once in the middle.

‘I don’t know how this was delivered to me,’ he said. ‘I found it on my dresser when I was in Petersburg. Someone must have broken in to deliver it.’

‘When?’ asked Aleksei.

‘July,’ said the tsar. ‘Read it.’

Aleksei read. The text was in French.

My Dear Aleksandr Pavlovich,

How have you been? Myself, I’ve had my ups and downs, but I’ve been patient. You and I are both newcomers to this affair, but I’m sure you know the details of the Romanov Betrayal as well as I do, perhaps better. Betrayal must always be avenged, sooner or later. For you, the day of vengeance is close at hand.

You will be leaving Petersburg soon to winter in a more pleasant climate. Make sure that you do not leave the country. Why not visit the Sea of Azov? My suggestion would be Taganrog, but I will easily find you wherever you choose to stay. Even if you choose not to stay in Russia, I will find you. Or if not I, then the person I represent. I’m sure you understand that it is better to face your fears.

It will take time for you to prepare for your journey, and I imagine that you will want to invent some excuse for your unexpected destination; rather that than have them all hear the truth. I will expect your arrival by the end of September.

Your devoted friend,

Cain

Aleksei read the letter twice, though the second reading was more to allow him to collect his thoughts than to garner any new information. He took only a moment to note that the letter was in the same hand as Cain’s notebook, regardless of the differences between French and English. It was no surprise that there was a connection between Cain and Aleksandr, but it shocked him to discover that His Majesty was already fully aware of it.

The tsar was sitting forward in eager expectation of Aleksei’s opinion, his head almost imperceptibly tilted to the left. Aleksei was well aware of Aleksandr’s deafness but, like everyone else close to His Majesty, he had never made any mention of it.