The medication appeared to work on him so swiftly that its initial effects must have been purely placebo. Its true pharmacological impact was evident after about an hour. I noticed a dimming of his eyes, a loss of co-ordination and a slackness in his facial muscles that was familiar to me from my visits to the mansion. At this point, he became very docile and manageable. I understood Bykov and Vera’s insistence on his taking the pills: they were to cushion his responses to the traumas of the everyday.

I helped him to the car, buckled him into the passenger seat and we set off. I thought the journey might send him to sleep, but the view from the window was more stimulant than sedative. Even in his medicated state, he watched the scenery intently.

As we drove, I found myself talking about Leonora – to have a confessor who was incapacitated by drugs and half insane was better than to have no one. He occasionally mumbled something unintelligible. Once he said a phrase I recognised as a quote from Johnson himself: ‘Life is a progress from want to want, not from enjoyment to enjoyment.’

The city was a log jam of traffic. I had to stick the car in the car park on Poland Street and we walked to Leicester Square. The medication which held Jack’s anxiety in check also affected his balance. He was like a huge, blinkered horse, stumbling through the streets, yet strangely unnoticed by the tourists and passers-by fixated on the self-conscious flamboyance of Soho.

I had texted Leonora to apologise. I had said I was sorry, and that whatever my feelings were, Lucius and Sarah needed us both to maintain some semblance of dignity as parents. But I didn’t feel able to introduce Jack to her. For one thing, it breached my oath of confidentiality to Vera. But the second and greater obstacle was his sheer outlandishness. In his unmedicated state, it might have been possible to pass him off as a visiting academic, but the way he was now, his eyes dulled from the drugs and walking unsteadily, he raised too many unanswerable questions.

Brief Encounter was showing in repertory at the Prince Charles Cinema. I got us both tickets and we made our way into the auditorium about ten minutes after the film had started. He was rapt by the spectacle. I’d bought a couple of meat pies and a gargantuan take-out cup of tea which I passed to him in the darkness. He received them warily. ‘Is it not opprobrious?’ he whispered. ‘I have no wish to earn the minister’s contumely.’

‘We’re not in church,’ I explained. ‘This is a …’ I looked at his puzzled face. I think at some preconscious level I had an inkling of the problem I was dealing with. I understood at least that I would have to compromise on certain elements of our shared reality. ‘This’, I said, ‘is a playhouse.’

Of course, I had misgivings about leaving him, but I reasoned that I would be gone for half an hour at the most. There was over an hour of the film to run. I unwrapped his pie and when I judged that his attention was firmly held by the film and the food, I told him I was slipping out to the toilet.

*

It took me eight minutes to get to the cafe on Charing Cross Road where Leonora and I had arranged to meet. There was no sign of her. I ordered an espresso and waited. Caspar’s big SUV finally pulled up, hazard lights flashing, and disgorged Leonora and the children.

There was a bittersweet delight in seeing the kids. Sarah gave me a kiss. Lucius, who appeared to have grown in the weeks since I’d last seen him, consented to an awkward hug. Caspar remained in the car with a sheepish expression on his face.

‘What’s all this about?’ I asked.

‘Mum’s playing in Paris tonight and we’re all going,’ said Sarah. ‘Der-brain forgot his passport.’

I’d like to think that in other circumstances Leonora and I might have welcomed the chance to talk to one another, but she was all business and eager to get on. Five minutes later, they were off, roaring up Charing Cross Road, like a brief intermission of happiness, a moving oasis of normalcy. You don’t need to be in a carcass to see what’s best about human existence, but it helps. As I walked back to the cinema, my thoughts circled obsessively around that car, moving off with my family into a future that I played no part in.

*

When I got back to the Prince Charles he was gone. Pie wrappers and the lingering scent of pear drops marked the place where we had been sitting, but there was no other sign of him. He wasn’t in the loo, and the usherette claimed not to have seen anyone leave. I raised my voice. The half-dozen heads in the auditorium turned to register their disapproval. Suddenly, I was hot with shame and panic.

There was a traffic policeman standing next to his motorcycle on the corner of Panton Street. I asked him if he’d seen a vulnerable adult, late fifties, bald, wearing tracksuit trousers and a grey T-shirt.

‘You lost someone, sir?’

‘I think I might have.’ The dyspeptic feeling of anxiety was building in the pit of my stomach.

‘Does he know the area, sir?’ he asked. ‘Is there anywhere he might go?’

‘Not really,’ I said.

‘Can you do any better on the description?’

I felt close to tears. I could find nothing to describe him. It takes detachment and a degree of composure to formulate a description. The quiddity of him was, in any case, hard to pin down. His silence. The odd smell. The eyes.

‘Are you a relative, sir?’

I told the officer I would carry on looking myself. For forty-five minutes, I jogged through the streets between Leicester Square, Shaftesbury Avenue and Charing Cross Road, until the fact of his disappearance became unignorable.

17

Misha Bykov took the news better than I had anticipated. My relief was quickly succeeded by a feeling of chagrin: his calmness stemmed from his assumption that I was incompetent. He’d been expecting something like this to happen.

The irony – again – is that, though I didn’t know it, I had very nearly found Jack without Bykov’s help. I learned later that he had tried to get into Black’s, the members’ club on Dean Street, and had been rebuffed. The altercation was considerable and I can only have missed it by a couple of minutes. But by the time I got there, Soho’s grimy and dissolute indifference had closed over the recent drama. It was all quiet, and a trio of crack addicts were hunched around a pipe in a doorway, their backs turned to the closed-circuit television cameras which supervised the street. There was no sign that Jack had ever been there.

Bykov met me in Bar Italia and listened in silence while I told him what little I knew. His big Mercedes sat in a loading bay opposite the cafe. Every parking attendant who came past quickened their pace when they saw it and then made the same disappointed swerve at the sight of its diplomatic plates. Bykov stirred three sugars into his espresso with a surprising daintiness and then drained it. ‘Come on, let’s go,’ he said.

I got into the Mercedes, which reeked of Magic Tree air freshener, and we drove to the Poland Street car park, in order, I assumed, to pick up my car. I was wrong. Bykov descended quickly to the deepest, most subterranean levels of the basement, parked in an obscure corner and gestured for me to get into the boot.

‘It’s a joke?’ I said.

‘Ne shutka,’ said Bykov. No joke.

There followed about half an hour of nausea-inducing darkness and joggling which culminated in my being helped out in a gloomy inward courtyard somewhere behind the St James’s Square mansion.

Bykov told me this was the only blind spot on the mansion’s cameras. He said it was important that Hunter and Sinan knew nothing of our connection. I had already had an inkling of his loyalty to Vera. It was only later that I understood the depth of his support for her.