A rouble would be more than two days’ pay, she knew, for many men. The watchman seemed to think a moment, then he nodded curtly, once, and pocketed the coin. ‘Be on your way, then.’

As the watchman stepped aside to let them leave the bridge, Dmitri took her elbow in a fierce protective grip, his own eyes fixed upon the grand front of the palace as they made their way towards its steps.

‘And what,’ he asked her, ‘did you go and do a thing like that for?’

Anna was not truly sure, because now she had only one rouble remaining and two more guards yet to be paid, but she replied, ‘He would have seen your knife.’

‘He’d not have seen it very long, for I’d have buried it within his thieving heart.’

‘Dmitri, please.’ Her glance implored him to be sensible. ‘I lost one escort earlier today to Mr Trescott’s tavern, and if I lost another to the gallows the vice admiral would not easily forgive me.’

The normally fearsome Siberian softened a little, and despite his pride he showed a grudging sort of gratitude by guiding her around a patch of roughened ice. But still he felt the need to point out that the watchmen of today had lost their manners altogether. And the palace guards were little better.

Anna shushed him as they neared the closest of the two stone flights of steps that climbed the porticoed façade of the great Winter Palace. Near the base of those steps stood not one but four guardsmen, and since she had no idea which one of them she was supposed to approach, she addressed them all, clearing her throat with a small, cautious cough.

‘I am come from the Vice Admiral Gordon,’ she said, ‘on a matter of business.’

All four guardsmen looked at her, and she’d begun to think that maybe none of them was the right guard, the one whom she’d been told to pay, until at last one of the younger guardsmen stirred and came across so that he stood quite close to her, his back blocking the view of the others as he held his open hand between them. ‘Let me see your business, then,’ he said.

When Anna put the one remaining rouble in his palm, he closed his fingers round it with a nod and told her, ‘Come this way. But only you, alone. Your man must wait.’

Dmitri frowned, but both of them knew better than to argue or to try to make demands, so he stayed back while Anna climbed the curving stairs behind the guard, who asked her, low, ‘There is a letter?’

‘Yes.’

He nodded for a second time, and led her through the shadowed, torchlit portico and past another guard into the palace. It was not as grand a place as she’d imagined it would be, although she realised she should not have been surprised by that, for Gordon had so often said the Tsar did not feel comfortable with grandeur. And she’d seen with her own eyes how much at ease the Tsar looked when he strode the streets himself, so tall above the men around him and with so much energy, yet dressed in nothing grander than his dark-green regimentals, with no wig nor fancy trappings and adornments to reveal his rank.

His palace, she decided, was much like the man – constructed with an eye to practicality and comfort, not to fashion. This reception room she stood in was not so unlike the rooms she walked through every day at the vice admiral’s house, save for the icon set high in the far-facing corner to serve as a focus of humble devotion. The doors, with their draught-blocking curtains drawn back at each side, stood wide open to other rooms leading beyond, and they, too, looked as unpretentious. Where she had expected to be dazzled, she instead felt welcomed, and the feeling gave her courage.

‘Wait here,’ said the guard, ‘and I will find the man you need.’

The man who would deliver the vice admiral’s letter to the Tsar. The man who would expect a silver rouble as his payment, when she had none left to give. She tried to think of what to do, of what to tell him, but her thoughts were interrupted by the male voice rising angrily within the room that opened to her right.

Through the door that stood ajar she could just glimpse a tall man’s figure entering the chamber from the room that lay beyond it, and when next his voice erupted Anna recognised it as the Tsar’s.

He raged, ‘You dare to ask for such a thing? For him? It is beneath you.’

The Empress Catherine – for, thought Anna, no one but the Empress would be brave enough to stand against the Tsar in such a temper – made reply more calmly, but as clear: ‘I have forgiven him. Why cannot you?’

‘You ask too much.’

‘You used to be forgiving.’

They were speaking, Anna thought, of Willem Mons; they must be. She had never lived with men so volatile, who gave vent to their anger at this volume, and it made her feel uncomfortable, uncertain whether she should cross to close the door and try to give them privacy.

The Tsar fired back, ‘How can you think that such a man is worthy of forgiveness? He has spat on all I stand for. All I’ve built. Do you not understand the damage he has done? My Russia, all that I have made, my whole life’s work – it stands, as all here in St Petersburg must balance, on the thin supports we drive into the swamp, and let but one of those foundations fail,’ he warned, ‘and everything will fall, and then the swamp will rise and swallow it again, you understand? And my supports, my pillars, these have been obedience and honesty. Above all, I would give my people honesty!’

‘I know.’

‘He smiled. He smiled while he betrayed my trust. While he betrayed you.’

Empress Catherine started to say something, but the Tsar was not yet finished.