‘Because it wasn’t important. The receipts for documents go upstairs and we keep those. This is just office stuff, you know, pens, photocopying fluid. Every couple of months we chuck it out.’

‘So anyone could have walked in off the street, asked for the docket and you would have given it to them?’

He looked back down at the file. ‘It says Ms Falkner here.’

‘Yes, but…’ I stopped. I’d realized the futility of pushing it any further.

Eight hours later, or thereabouts, I was drunk. In the afternoon I had phoned Gwen and Mary, left messages and assumed they were busy, out of town or understandably sick of hearing from me. Of hearing about me. Of even knowing I existed. But later in the afternoon, Gwen rang and said that the two of them were taking me out. I had that infallible sixth sense when you know that people have been talking about you and making arrangements for you without your knowledge. I told her it was very kind of her but it was a Monday night and they had lives to lead. Gwen said that was nonsense. I had to put a dress on and they would pick me up at eight.

They took me to a new Spanish bar in Camden Town where we ate tapas with little glasses of dry sherry, then had more tapas and more sherry, and then we got into a discussion about what our favourite drink was. Someone said a dry martini and Mary said it should be served with a twist of lemon peel and Gwen said it should be with an olive. So we had one with the lemon followed by one with the olive. I was given the casting vote as to which was the winner, so I chose the lemon peel and we had to have another of those to celebrate.

It was at that point, as I was taking a delicate sip of my third dry martini, that Gwen asked how I was. Even in my alcoholic stupor, I realized that this was what the whole evening had been leading up to. My messages on their mobiles must have sounded terrifyingly abject and they had clearly decided something needed to be done.

‘I’m all right,’ I said.

‘No,’ said Mary. ‘This is us.’

I thought for a moment and I – or perhaps it was the gin on my behalf – saw things with a new clarity.

‘I am, really,’ I said. ‘In a way. There was something wrong with me, but now it’s different. It’s the things around me. I know you’re getting tired of Widow Falkner and her endless tales of woe, so I’ll give you the short version.’

Well, fairly short. I told them the events of the previous days in as compressed a way as I could manage. At the end of it, Mary and Gwen exchanged an alarmed, confused glance. I drained my glass. ‘I mean, what would be the point of giving the police an alibi that I knew wasn’t true, then removing the evidence before they could check it? I mean, what’s the point of that? How would you explain it?’

There was a pause.

‘There must have been a mix-up of some kind,’ said Gwen.

I was now having to concentrate very hard to speak, let alone think. ‘I keep trying to think of logical explanations,’ I said, ‘but all I come up with are illogical ones. For example, I thought that maybe one of you went down there to check whether the alibi was right, found it wasn’t and took it away to protect me. But you wouldn’t do that, would you?’

‘Of course not,’ said Mary.

‘We should have had margaritas,’ said Gwen. ‘Martinis are too dangerous.’

‘You can’t have margaritas here,’ I said. ‘Margaritas are Mexican. They’d be offended.’

‘But martinis are even foreigner,’ said Mary. ‘More foreign.’

We came out of the bar as it was closing and the cold air seemed to clear my head immediately. I hugged my friends and thanked them.

‘You don’t think the police will arrest you, do you?’ Gwen said. ‘They can’t. Not really.’

I pulled my coat tightly around me to protect me from the wind whistling up Camden High Street. Suddenly things came into focus.

‘I don’t know,’ I said. ‘I’m not sure if it all fits together. If suddenly I was found dead and it looked as if I’d killed myself, it would be good enough. A grief-stricken widow, a guilty murderer who felt the net closing over her and couldn’t take the pressure any more. They would be able to close the files on three cases at the same time. If the pieces didn’t quite fit, if it didn’t make complete sense, well, life’s messy, isn’t it? But it would be good enough for the police.’

‘Ellie,’ said Gwen, horrified, ‘you mustn’t say that.’

I saw a taxi and raised my arm to hail it. ‘But if anything happens to me,’ I said, ‘you’ll remember I said it, won’t you?’

I went to bed exhausted, but my nerves were jangling, my mind racing and I knew that sleep was impossible. I tried every trick I could think of to make my brain forget about trying to go to sleep so that it could just go to sleep. I relaxed, I concentrated, I mimicked a supposedly sleep-like regular breathing, eyes closed. I opened them, stared into the darkness and said to myself, That’s what blind people see. I tried to think of something boring, I tried to think of something interesting. I began to wonder how I had ever managed to fall asleep in the past. How can you manage an action that isn’t an action, but instead just a letting-go? I became obsessed with the idea that you can never observe yourself going to sleep, in the same way – I supposed – that you can never experience yourself dying. So I began to think that there must be an earlier falling-asleep you do before you fall asleep, like the pre-med before an operation, so that you don’t observe yourself falling asleep. But you’re not conscious of that either, so that must be preceded by another, and another, so that actually it’s impossible ever to fall asleep.

As a deranged way of trying to tire myself out and force myself into unconsciousness, I went for a journey in my head, as if thinking about something was as tiring as doing it. I walked out of the house, turned left, then left again and went down to the canal, past Camden Lock through Primrose Hill, then out into Regent’s Park, along Euston Road and back through Somers Town, Camden Town and towards home. It was like a feverish dream, except that I was awake and in control of it.

At first I tried to imagine it as a simple walk through the city but then I had the impression I was being chased, but I couldn’t see who was behind me, couldn’t tell whether I was being pursued by one person or many, or even whether it was a person or a thing. I just had the feeling that people were out there and that they were hostile to me. Suddenly, overwhelmingly, I knew that on my imaginary trek I wasn’t being hunted. I was looking for something, following something and I realized it was you. I wasn’t just looking for you but I started talking to you and I wondered whether it made any sense for me to talk to you, whether you existed outside my mind and the minds of people who knew you. Was some remnant of you somewhere in some darker dark than the dark in which I was lying? If I didn’t believe you were out there somewhere – and I didn’t, not really – it didn’t make sense for me here, in the dark, to talk to you, and you were ‘him’ again, Greg, a thing, something past and gone.

Suddenly the temptation to yield not only to sleep but to death felt irresistible, leaving the harsh noises and bright lights, the jabs, pains and torments of life for the absence, for the nothingness, to join you, to be with you, or at least to share nothingness with you. For a time, as I lay there, listening to sounds from outside, watching the beams of headlights crossing the ceiling, I felt that anyone who killed me would be doing me a favour.

I lay in bed, peacefully, stolidly awake, for what must have been hours, waiting for the curtain edges to grow light, and then I realized that the shortest day of the year had only just passed and that daylight was still far away. I fumbled for my watch on the bedside table, knocking a lamp over. It was just after five. I got out of the bed, pulled on jeans, a shirt, a sweater, a thicker sweater on top of that, walking boots, then a bulky jacket of the kind you might wear on a trawler and a woolly hat. I left the house and started to walk, not as I had in my waking dream but northwards.