‘Not at all. It’s important that I don’t underestimate the obstacles that still confront the gospel. I intend to acknowledge my great debt to you in the book.’

‘That is very kind but not necessary.’

‘Of course, if you prefer to be anonymous, for any reason, I will respect that.’ Notovitch’s look is weighted with a wounded heaviness. He’s authorising any future denial. At that instant, Vincenzo feels a terrible pity for the old man and his vast loneliness. He remembers the hostile salesman in Hatchards. The distrust based on nothing. He recognises a commonality with Notovitch. A line from Deuteronomy: Love ye, therefore, the stranger, for ye were strangers in the land of Egypt. ‘It would be an honour to have my name in your book.’

‘Very well. As soon as I reach home, I will wire you the money for the transcripts. In the meantime, keep the cylinders safe.’

At Victoria station, a porter checks the luggage tag on Notovitch’s steamer trunk and hoists it onto a trolley. The concourse is spotted with pats of dried chewing gum.

After agonising over the parting gift, Vincenzo settled on a book from a dealer on Charing Cross Road: a copy of The Divine Comedy in Italian. Notovitch seems genuinely surprised and moved. He whistles at the porter and gestures for him to return. He unclasps the trunk and opens the lid. From inside, he removes an object which he presses into Vincenzo’s hands. Skobelev’s flask.

Too much? I think so. It feels a little Hollywood. Perhaps it’s MacGahan’s chapan instead, tied into a bundle with knotted string and naphthalene-impregnated paper.

That doesn’t seem right either.

How about this: perhaps he takes out a billfold, removes two five-pound notes and hands them to Vincenzo?

No, that’s completely wrong – that last gesture only demeans both men.

Perhaps the precise detail is unimportant.

Do they embrace? Definitely not. They shake hands with a certain guarded respect, knowing there is no basis for friendship and little chance of meeting again.

The guard blows his whistle. Notovitch gets aboard. The train departs.

4: CONVOY SIXTY-EIGHT

LOOK: A COLOURED MARBLE TURNING IN A SEA OF INK. As it rotates, slowly, anticlockwise, the dark line of approaching sunset gobbles a continent puckered with mountains and vast belts of olive forest. Distant wind shirrs the blue enamel of its oceans. It is an earth. Not exactly the earth, but a planet very much like ours.

You recognise this church. In our world, it’s called the Saviour on Blood. Here it has other names: khram Khristusa neschetnykh del, the Church of Christ of Myriad Things, or, more formally, the Church of the Pleroma.

Inside, the walls are covered with mosaics that tell a story you’re familiar with: a shaven-headed man drinks water from a cleft rock; here, he sits in contemplation among orange-robed adepts.