The letter was dated Thursday morning.

My Dear Mr Grant,

Or should I say Inspector? Oh, yes, I know about that. It did not take me long to find out. My excellent Mahmoud is a better detective than any of your well-meaning amateurs on the Embankment. But I shall not give you your rank, because this is a social communication. I write to you as one unique human being to another worthy of his attention. Indeed, it is because you are the only Englishman who has ever moved me to even a momentary admiration that I present these facts to you and not to the Press.

And because, of course, I am sure of your interest.

I have this morning had a letter from my follower, Paul Kinsey-Hewitt, announcing his discovery in Arabia. The letter was sent from the Morning News office at his request, to anticipate the publication of the news tomorrow morning. A piece of courtesy for which I am grateful to him. It is ironic that it should have been the Kenrick youth who was responsible for bringing to him, too, the knowledge of the valley’s existence. I saw a great deal of the Kenrick youth while he was in London and I could find nothing in him worthy of so great a destiny. He was a very common-place young man. He spent his days flying a mechanical contraption mindlessly across deserts that men had conquered only with suffering and resolution. He was full of a plan whereby I should provide the transport and he should lead me to this find of his. But that of course was absurd. I have not lived my life and made a great name in the desert to be led to discovery by an instrument-watcher from the back streets of Portsmouth; to be a transport provider, a camel-hirer, for some other man’s convenience. It was not to be thought of that a youth who by a climatic hazard, a geographical accident, had stumbled on one of the great discoveries of the world should be allowed to profit by it at the expense of men who had given their lives to exploration.

As far as I could judge, the young man’s only virtue (why do you waste your interest on so dull a piece of human mass-production?) was a capacity for continence. In speech, of course; please don’t misunderstand me. And it was important from my point of view that the tongue which he had held with so rare a continence should go on being unwagged.

Since he had arranged to meet another of his kind in Paris on the 4th (poor beautiful Lutetia, for ever raped by the barbarian) I had a little less than a fortnight to contrive this. I did not in fact need the fortnight. I could have achieved my end in two days if necessary.

I had once, when travelling to Scotland by night, stayed awake to write some letters and post them at Crewe when the train would reach its first stop. I had thought then, as I sat looking at the platform after getting rid of my letters, how easy it would be to leave the train unobserved. The attendant stepped out to receive late-joining passengers and then went away on affairs of his own. There was a long wait at a quite deserted platform while luggage was loaded into the distant vans. If one had managed to travel so far unaccounted for, one could step off the train and no one would ever know that one had been on it.

That memory was the first of the two props for my inspiration.

The second was my possession of Charles Martin’s papers.

Charles Martin was my mechanic. He was the only European and the only technician (what an appropriately deplorable word!) ever employed by me. I engaged him for the least successful of my expeditions, the semi-mechanised one, because my Arabs (though learning rapidly, alas!) were not skilful with machinery. He was a repellent creature, interested in nothing but internal combustion and the avoidance of his share of camp duties, and I was not sorry when he died in mid-desert. We had by that time found the vehicles a liability rather than a help and had decided to abandon them, so Martin had already outlived his usefulness. (No, I had nothing to do with his death; Heaven in this instance did its own scavenging.) No one asked for his papers, and since the journey was from coast to coast we never returned to the town in which I had engaged him. His papers lay in my baggage, a matter of no interest to me or to anyone else, and came back to England with me.

I remembered them when it was necessary to silence the Kenrick youth. Kenrick looked not too unlike Charles Martin.

It was Kenrick’s plan to go back to his Carter-Paterson occupation in the East until such time as I should join him there, and we should then set out on our expedition together. He came to see me at Britt Lane very often, to discuss routes and plume himself on the prospect in front of him, and it amused me to see him sit there and babble his nonsense when I had so strange a translation prepared for him.

He had arranged to go to Paris by the night-ferry on the 3rd. He ‘collected’ ferries, it seemed. He would go many miles out of his way to be punted across a stream which he could have crossed by a bridge a few yards from where he was standing. The Dover ferry was to be his two-hundredth, I think. When he told me that he had booked a berth on the train-ferry I telephoned, as soon as he had gone, and booked a berth to Scoone in the name of Charles Martin for the same night.

When I next saw him I suggested that since I was going to Scotland on the same evening on which he was leaving for Paris, he should leave his luggage (he had only two suitcases) in the cloak-room at Victoria, dine early with me at Britt Lane, and see me off at Euston.

He was always delighted to fall in with any suggestion that I was moved to put to him, and he agreed, as I knew he would, to this. We dined, on a rice and cutlets and apricots dish that Mahmoud has taught Mrs Lucas to make (it needs long cooking so that the dish is impregnated with the flavour of the apricots) and Mahmoud drove us to Euston. At Euston I sent Kenrick to pick up my sleeper ticket while I went ahead. By the time Kenrick rejoined me I had found my compartment and was waiting on the platform for his arrival. If by chance he wondered why I was travelling as Charles Martin I had the excuse of my fame to account for an incognito. But he made no comment.

I felt that the gods were on my side when I saw that the attendant was Old Yughourt. You will not know Old Yughourt. He has never in the whole course of his career been known to take an interest in any passenger whatever, his chief object when on duty being to retire to his own unsavoury compartment at the earliest possible moment and go to sleep there.

We had less than five minutes before the train was due to depart. We stood talking for a little with the door half-closed, Kenrick facing the corridor. Presently he said that he had better get out, or he might be carried to the Highlands. I indicated my small overnight case which was lying beside him on the bunk and said: ‘If you open my case you’ll find something in it for you. A keepsake till we meet again.’

He bent over, with an almost childish eagerness, to unfasten the two locks. The position was perfect. I took from my pocket the most satisfactory weapon ever devised by man for the destruction of his unsuspecting enemy. Primitive man in desert countries had neither knife nor rifle, but he made the sand serve. A rag and a few handfuls of sand, and a skull would crack like an egg-shell; very neatly it would crack, without blood or fuss. He gave a small grunt and fell forward over the case. I shut and locked the door and looked to see if his nose was bleeding. It was not. I dragged him off the berth and bundled him under it. This was my only miscalculation. One half of the space under the berth was occupied by some permanent obstruction, and thin and slight as he was his knees could not be pushed back out of sight. I took off my own coat and flung it on the berth so that it hung over and hid his legs. As I arranged the folds in a manner at once concealing and suitably casual, the whistle went. I put the outward half of my ticket to Scoone, together with my sleeper ticket, on the small shelf below the mirror where Yughourt would see it, and walked down the corridor to the lavatory. No one had interest for anything but the moment of leave-taking. I shut myself into the lavatory and waited.

About twenty minutes later I heard the successive closing of doors that meant that Yughourt was making his rounds. When I heard him in the compartment next door I began to wash, noisily. He tapped at the door a few moments later and asked if I were the passenger in B Seven. I said that I was. He announced that he had found my tickets and taken them. I heard him go through to the next coach and begin his door-slamming, and I walked back to B Seven and locked myself in.

After that I had three uninterrupted hours to make all perfect.

If you ever want to be sure of uninterrupted peace, my dear Mr Grant, buy yourself a sleeper ticket to the North of Scotland. There is nowhere in this world where one is so safe from interruption as one is in a sleeping compartment once the attendant has done his round. Not even in the desert.

I retrieved Kenrick from below the bunk, rubbed his head on the edge of the wash-hand basin, and laid him on the bunk. An examination of his clothes showed a gratifying cosmopolitanism. His underclothes seemed to be dhobi-washed, his suit made in Hong Kong, and his shoes in Karachi. His watch was a cheap metal one with neither name nor initials.

I removed the contents of his pockets and substituted Charles Martin’s pocket-book and its contents.

He was still alive, but he stopped breathing as we were running through the yards at Rugby.

From then on I dressed the set, as they say in the theatre. And I don’t think that I missed anything; did I, Mr Grant? The details were perfect, even to the crushed hairs in the wash-hand basin and the dusty palms of his hands. In the case that I was leaving behind were old clothes of my own, well-worn and washed, and of a type that he was in the habit of wearing; and such Frenchness as I had been able to supply from my own store: a novel and a Testament. The case also, of course, contained the all-important bottle.

Kenrick had an extraordinarily hard head. I refer to the matter of drink, of course, not to the results of sand-bagging. I had plied him with whisky at dinner, and had offered him a stirrup-cup of such dimensions that any other man would have blenched at the prospect. He did indeed look at the half-tumbler of neat whisky a little doubtfully, but, as I have said, he was always anxious to please me and he drank it down without protest. He remained sober; or to all appearances sober. But both his blood and his stomach would be whisky-sodden when he died.

So was his compartment when I had finished with it. As the lights of Crewe began to go by I put the final touch. I laid the half-full bottle on the floor and rolled it to and fro over the carpet. As the train slowed down I unlocked the door, shut it behind me, walked away down the train until I had several coaches between me and B Seven, stood looking in a casual, interested way at the traffic on the platform, stepped, still casual, down on to that platform and strolled along it. In hat and coat I did not look like a passenger and no one took any notice of me.

I came back to London on the midnight train, arriving at Euston at half-past three, and was so exhilarated that I walked all the way home. I walked as if on air. I let myself in, and was sleeping peacefully when Mahmoud came to call me at seven-thirty and to remind me that I had an appointment to entertain Pathé representatives at half-past nine.

It was not until you called to see me that I knew about the scribbled words on the newspaper that had been in his coat pocket. I admit that I was for a moment dismayed that I should have overlooked anything at all, but I was instantly comforted by the venial nature of the slip. It did not in any way detract from nor endanger my unique achievement. I had let him keep his deplorable rag, as a piece of set-dressing. That it proved to have Kenrick’s handwriting on it would not be of interest to authorities who had accepted the young man as Charles Martin.

The following evening, at the rush hour, I drove myself to Victoria and retrieved Kenrick’s two cases from the cloak-room. I took them home, removed from them all maker’s marks and easily identifiable articles, sewed them both up in canvas, and sent them with their contents to a refugee organisation in the Near East. If you ever want to get rid of anything, my dear Mr Grant, do not burn it. Post it to a remote island in the South Seas.

Having seen to it that the admirably reticent tongue of the Kenrick youth would stay reticent, I looked forward to enjoying the fruits of my labours. Indeed, yesterday I had assurance of sufficient backing for my new expedition, and had planned to fly out next week. The letter from Kinsey-Hewitt this morning alters all that, of course. The fruits of my achievement have been taken from me. But no one can take from me the achievement itself. If I cannot be known as the discoverer of Wabar, I shall be known as the author of the only perfect murder ever perpetrated.

I cannot stay to be a candle-holder at Kinsey-Hewitt’s triumph. And I am too old to have more triumphs of my own. But I can light a blaze that will make the candles on the Kinsey-Hewitt altar look small and pale and uninteresting. My funeral pyre will be a beacon to light all Europe, and my achievement in murder a tidal-wave that will sweep Kinsey-Hewitt and Wabar into the waste-paper baskets of the world’s Press.

This evening, at dusk, I light my own pyre, on the highest slope of the highest mountain in Europe. Mahmoud does not know this. He thinks we are flying out to Athens. But he has been with me for many years and would be very unhappy without me. So I am taking him with me.

Good-bye, my dear Mr Grant. It grieves me that someone of your intelligence should be wasting his talents in that rather stupid establishment on the Embankment. It was clever of you to discover that Charles Martin was not Charles Martin but someone called Kenrick, and I salute you. What you are not clever enough to discover is that he did not die by accident. What no one would ever be clever enough to discover is that I am the man who killed him.

Please take this letter as a mark of my esteem and pour prendre congé. Mrs Lucas will post this on Friday morning.

H. C. Heron Lloyd.

Grant became aware that Mrs Tinker was showing Tad Cullen into the room, and that she must already have been in without his noticing because the envelope from the Yard was lying beside him on the desk.

‘Well?’ said Tad, his face still thunderous. ‘Where do we go from here?’

Grant pushed over the pages of Lloyd’s letter for him to read.

‘What’s all this?’

‘Read it.’

Tad took the thing up doubtfully, looked for a signature, and then fell on the manuscript. Grant put his thumb in the envelope from Cartwright and broke it open.

When Tad had finished he looked up with a shocked face and stared at Grant. When at last he spoke what he said was: ‘I feel dirty all over.’

‘Yes. It is an evil thing.’

‘Vanity.’

‘Yes.’

‘That’s the crash that was in the evening papers last night. The crate in flames on Mont Blanc.’

‘Yes.’

‘So he would have got away with it after all.’

‘No.’

‘No? He had thought of everything, hadn’t he?’

‘They never think of everything.’

‘They?’

‘Murderers. Lloyd forgot so obvious a thing as finger-prints.’

‘You mean he didn’t do that job in gloves? I don’t believe it!’

‘Of course he did it in gloves. Nothing he touched in that compartment would have any print of his. What he forgot was that there was something in that compartment that he had handled before.’

‘What was that?’

‘Charles Martin’s papers.’ Grant flipped them with his finger-tip where they lay on the desk. ‘They are covered with Lloyd’s prints. They never think of everything.’