When, though? Did the attack slip from fact to fiction during the writing? Possibly, but I suspected that Night Traffic became a fraud in Pierce’s mind later than that, once it became a success, and he was called upon to talk about it again and again, and to repeat and relive the events of that night over and over. Writing is abandoning. In making a record of our thoughts and experiences, we give ourselves permission to forget them. We put down our words – we leave them. But sometimes they get picked up, and brought back to us. I only knew this sensation in a small way, in my continual efforts to escape what I had written, and its mistakes and borrowings and fabrications. For Pierce the sensation must have been multiplied a thousandfold. At some point, sitting on a BBC sofa, his damaged mind had decided that it had created the pain that he was experiencing. The source of the inner conflict was obvious. There was a fraud in Night Traffic, in a way, a more sympathetic one: the book was an account of how writing had helped him heal. But he was not healed, far from it. There was the lie, or at least the error. And as he was obliged to endlessly repeat it, it contaminated the entire narrative.

So he retreated from view – and then Quin’s unblinking eye was turned on his file cabinets, and the polite burglars started rifling through his office … The cognitive dissonance must have been intolerable. Inventing the fraud had safely bottled up the attack in the realm of fiction; but was the fraud real if it existed only in Pierce’s head, as a story he told only himself? No – stories can’t work like that. It had to be shared, it had to be confessed. And who better to serve as witness to this confession than Quin, pious arbiter of digital truth, the man fanatically sifting London’s facts from its myths?

That prig, Quin.

I halted at the portal of Mile End Underground Station. The bright pool of light at the head of the steps, the sober white lettering of the station sign, the nicotiney tiles, the warm waft of the tunnels, a haven of electricity and dust – it was all so reassuring, it was unbearable. My knees buckled and I retched. Staggering, I struck a recycling bin, and I steadied myself against it, belching swampy fumes, trying to regain control. My head throbbed. When did I last drink? In Pierce’s apartment – but the memory was interrupted, kicked, by bursts of image. When Pierce said he could see the plume. When we saw the burning car. When we saw the others in the clearing, surrounding us. When Pierce recognised them. When I saw the knife in Pierce’s hand. When I saw the drone. They hit me one by one, each a perfect shard of terror – no, facets of a united terror, catching the light in sequence, like a turning gemstone. Only now could I see the whole thing, and find that I could not take it as a whole. I had been in fear, the whole time, and now I was safe. Because there was another light flaring in my gathering recollection of what had just happened: why did Pierce have the knife?