“Derek’s difficulty was this—he didn’t want to commit suicide; not so much because he cared about his life, as because he didn’t want his cousin to get the legacy. He had, therefore, to create the impression that he was dead, with Nigel’s complicity; he had also, without Nigel’s complicity, to create the impression that he had been murdered. What steps he took to create the impression that he was dead, Nigel has already told us. They weren’t very clever ones; they were, I take it, the invention of Derek in his normal state. To disappear and leave a canoe floating about on a river, to lie low until your death is presumed, to start again in the Colonies under a fresh name—all that is a sufficiently clumsy idea, and a hundred accidents might have upset the plan. But the steps he took to create the impression that he had been murdered were, at least in their outline, very ingenious; I give them full marks for ingenuity. They were Derek Burtell’s Kubla Khan. Tell me, Leyland, why have you and I assumed up till now that it was a murder?”
“Because it seemed certain that some human being had been with Derek after the moment when Burgess lost sight of him at the lock.”
“Exactly. And what is our evidence that Derek Burtell was not alone during all that time?”
“The photograph; or rather the two photographs. No, a man can take a snapshot of his own footprints. But he can’t take a photograph of his own body lying stretched full-length in a canoe. Don’t tell me he did it by some arrangement of strings, because I won’t believe it.”
“No, that’s what’s been at the back of our minds all the time, imposing on us the idea of murder, or at least foul play. But what if the figure in the canoe was not really Derek’s, but somebody else’s? The hat, remember, was drawn over the face.”
“But the chin was Derek’s.”
“It was a Burtell chin. But are you sure it was Derek’s, and not Nigel’s?”
“But, hang it all, that doesn’t make things any clearer. He couldn’t photograph Nigel if Nigel wasn’t there. And if Nigel was there, Derek wasn’t alone.”
“Yes, I ought to explain, I suppose, that the photograph of Nigel was taken by Derek much higher up the river, near a place called Ditcham Martin. There is a light bridge over the river there, very much like the one at Shipcote Lock; it’s a common type, you know, except for the cement steps. Derek persuaded his cousin to take some of the drug, just to try it; you remember Nigel told us that it ‘laid him out.’ It did lay him out, on the floor of the canoe. Derek got on shore, let the canoe drift, and hopped up on to the bridge with the camera. The next film to be exposed was Number Three; Derek didn’t expose that, nor Number Four, nor Number Five. He turned the spool on to Number Six, and with Number Six he took a snapshot of his cousin as he floated under the bridge. Then he turned the spool back again to Number Three; not difficult to do, though of course he must have had to get a darkened room to do it in.”
“And this happened, I suppose, in the evening? That’s why the shadows went from left to right instead of right to left.”
“No, that’s the funny thing. Derek was careful to take his photograph at the right time of day, soon after breakfast. But he’d forgotten that on that particular bend the river is flowing south, or nearly south; you can see it on the map here. So that was that. Long before the cousins reached Millington Bridge, the sixth film contained damning evidence of Derek’s murder—at least, Derek thought so.
“Now we can take the story in its historical order. At the Blue Cow, a little above Millington Bridge, Derek suggested to Nigel that idea that they should sleep in separate places. Derek himself would put up at White Bracton, a mile or so from Millington Bridge, while Nigel came to the hotel at Millington Bridge twice over, and so created the impression that they both slept there. Thus, at White Bracton, the useful Mr. Anderton would come into existence; he was to be Derek’s future alias. Only, without telling his cousin, Derek altered the plan. He caught a late bus, and went all the way on to Witney. Nor, at Witney, did he give the name of H. Anderton. He gave the first name that came into his head—his imagination, you see, had broken down; and that was the name ‘Luke Wallace,’ which he had seen on a packet of letters in the letter-rack at the Blue Cow. Observe that Derek had now got a new name and a new address, of which Nigel could suspect nothing.
“By bus, or perhaps by an early train, he reached Millington Bridge in good time on Monday morning. He pretended that he had slept at White Bracton, but not very well; he pretended, therefore, that he was sleepy, and appeared to doze off on the floor of the canoe. In fact, he was pretending to be already a corpse. You, Mr. Farris, could not have sworn in a court of law, could you, that both passengers in the canoe were alive?”
“Quite certainly not. To tell the truth, it gave me a slight shock when I saw Derek lying so motionless. But then I remembered that he was said to be addicted to drugs, and thought that explained it.”
“I see. Nor did Burgess at the lock see Derek move, or hear him speak. He did speak to Nigel from the canoe; but by that time the water had sunk low, and the lock walls prevented any sound reaching Burgess’ ears. In a court of law, Burgess would have had to depose that
