Angela brought out six prints. She laid them before her husband one by one, tantalizing his curiosity by insisting that he should have a good look at each as it came.

The first print represented a board with the title “Church Notices”; and underneath this title appeared a lurid poster of a cinema performance, combining a maximum of thrill with a minimum of clothing. It was obvious that the finger of the humorist had been at work; that two photographs had been taken on the same film.

The second was a closeup view of a particularly distressing gargoyle, probably attached to the same Church porch.

The third represented a group of cows, knee-deep in the river, regarding the camera with that patient curiosity which cows register at the sight of any human activity.

The fourth, also taken from the river, showed a thin promontory of land, overgrown with a wealth of garden flowers; in the centre of these stood the figure of a stalwart gardener, from the waist downwards.

The fifth, taken at an irregular angle which played havoc with the perspective, looked down a flight of apparently stone steps, on each of which a footprint was discernible, though only those halfway down were sufficiently in focus to be clearly distinguished. The camera itself had obviously been held on a tilt, as if a very inexpert performer had manipulated it. At the sight of this Bredon whistled sharply.

The sixth was a view of the river, taken from a bridge; this was sufficiently indicated by the appearance of what looked like an iron girder, much out of focus, at the bottom of the picture. In the centre, fully focused, floated a canoe, which seemed to be nearly parallel to the bridge, nearly broadside on to the flow of the river. The water was slightly rippled, and a paddle, lying across the centre of the boat, made no clear reflection. The figure of a man lay sprawling at full length on the floor of the canoe, the knees just under the front thwart; the head was turned sideways, and was propped up by a rest and a cushion. The whole attitude suggested a complete abandonment of repose; something about the bend of the neck, something about the way in which the left arm lay crushed under the body, suggested that it was not the attitude in which a man would naturally have fallen asleep. A hat shaded most of the face, but revealed a clean-shaven chin. The back seat of the boat was empty; the other paddle leaned carelessly against it.

“Is he d-dead?” asked Angela, her hand on her husband’s shoulder.

“Dead, or dead drunk, or drugged, perhaps. I think the person who took this picture meant us to think he was dead, anyhow. He’s not a very pretty sight, you see, in any case. On the face of it, I must say it looks as if somebody had⁠—well, had finished him off and then taken a photograph of him.”

“But that’s rather horrible. It seems so disgustingly cold-blooded.”

“It needn’t have been the murderer, of course. It might have been somebody who found him lying dead⁠—apparently dead⁠—and thought it important to have a snapshot of him looking like that. Anyhow, the man who took that photograph is the man we want to get hold of. He must be able to give us news of Derek Burtell which is later than the lock-keeper’s.”

“You’re certain it was taken at the lock-stream bridge? Oh yes, of course, the footprint-photograph shows that.”

“Even if it didn’t, there could hardly be any doubt. You haven’t looked attentively enough at Number Four, or you’d have recognized an old friend.”

“Oo, is that Mr. Burgess?”

“There’s no doubt about the lock and the island. There can’t be two locks arranged like that. Now, you say this throws suspicion on Nigel Burtell. Let’s hear how you’d work it out.”

“Dash it all, it makes him out such a perfect brute. But you say he is one. Let’s assume that his alibi is all wrong; that he didn’t really take the train to Oxford at all, but went there by a fast motor⁠—if he ever did go to Oxford. No, that won’t do; he couldn’t get to the motor soon enough. Let’s say that he didn’t go to Oxford at all, for the sake of argument. That gives him all the time there is. He waits till Mr. Burgess’ back is turned, which doesn’t seem to be a very difficult thing to do; then he slinks down along the island, through the woods, and lies in wait for the canoe. Let’s say that his cousin is under the influence of a drug; that seems probable enough. He leaves his camera on the bridge, then goes down a little lower, takes off his clothes, and puts them there all ready. He comes up above the bridge again, swims out to the canoe as it floats by, and⁠—then I suppose he does something horrible, stabs his cousin with a hatpin or something. He swims to the bridge, ahead of the canoe, climbs up the framework of the bridge, and takes his photograph from there. Then he runs down the steps, all wet, and swims out to the canoe again; brings it in to the bank, and puts on his clothes. Then he sits down in the stern of the canoe, as if nothing had happened, and paddles it down a good long distance. He ties a weight to the body, digs a hole in the bottom of the canoe, gets out and makes tracks for the high road, or perhaps for Wheathampton Station. It doesn’t seem to work out awfully well.”

“What an imagination you’ve got! But there’s one point, don’t you see, where you must be wrong. He took a photograph of the footprints before he took a photograph of the body in the canoe. Therefore the footprints were made before he climbed up on to the bridge, not after he went down.”

“Blow, I’d forgotten that. But then how do you account for the footsteps going down, not coming up?”

“He walked up the stairs backwards. You can see that, if you look at the photograph carefully. The marks are the marks of heels. You don’t walk downstairs on your heels, you walk on your toes and the flat part of the soles. These marks show that he walked up backwards.”

“But why backwards?”

“Possibly just to create confusion. More probably because the prints of his toes might, in the millionth chance, have given him away. If he’d a hammer toe, for example, that would show up quite clearly. I dare say Messrs. Wickstead would be able to provide us with a very nice sketch of Mr. Nigel Burtell’s foot. But heels are so much alike, you can’t put in any Bertillon-work on them.”

“Yes, I suppose that’s true.”

“But there’s another thing. Nigel, if it was Nigel, hadn’t been in the water when he climbed that bridge.”

“I don’t see how you make that out.”

“Why, if one’s been in the water one drips. A few drops would have been bound to fall on the steps, and then they would have been reproduced in the photograph. Since there are no marks except the footprints, it’s clear that the prints were made by somebody who had nothing on, or anyhow nothing on his feet, who had not yet been into the water.”

“Why were his feet wet, then?”

“Because he’d been walking in the long grass, which was still wet from the night’s rain. I imagine it had been raining in the night.”

“Why should it have been?”

“Because, if you will look carefully at Exhibit Four, you will see a puddle.”

“Golly, what a man!”

“I suppose, then, that Nigel, if it was Nigel, did leave his clothes a little below the bridge. He walked through the wet grass, and, realizing that his wet feet would leave prints, which might conceivably be examined by some passerby, went up the steps backwards.”

“But I still don’t see what he wanted to photograph the footprints for.”

“I’ve no reason to think that he did want to. All we know is that he did. I don’t know if you often go upstairs backwards, but if you have the habit, you will realize that it’s apt to make your stance a little uncertain. And if you are carrying a camera at the time, it is quite possible for some slight lurch to make you pull the trigger by mistake. Then, realizing that you’ve pulled the trigger, or fearing that you have, you pass on from Number Five to Number Six. Number Five doesn’t look to me like a photograph taken on purpose. It’s all skew-eyed, you see.

“I see. Then he photographed his man first, and murdered him afterwards?”

“I don’t know that he murdered him at all, in the way you mean. I think, after he’d taken the photograph, he let himself down by the framework of the bridge, put the camera on board, and pushed the canoe gently in to the bank, where his clothes were. Then he dressed again, sat down in the stern, and paddled on. I don’t think he dug a hole in the canoe and left the man in it to drown. I think he drowned his man first, tying a weight on him, I suppose, or getting him under a bank somewhere, and then scuttled the canoe. If you look carefully, you can see that the hole in the canoe was made from the outside, not from the inside. It’s bigger on the outside, on the inside it’s quite small, not the size of a threepenny bit. He must have hauled the bows of the canoe out of water to do that, and it would be easier to do it when the canoe was empty. Besides, I take it he didn’t want to run any risks of a rescue. He saw to it, while he was about it, that his man drowned all right.”

“And you do really think it was Nigel Burtell?”

“I do and I don’t. He’s got a perfect alibi, as far as we know. Yet he stood to gain by the whole thing, because the money was coming to him. I love my Nigel with an N, because he was needy. I hate him with an N, because he was nowhere near. I don’t see what to make of it. The old lady at Spinnaker Farm told me that a gentleman came through that morning in a tearing hurry, wanting to catch a train. I suppose that must have been the nine-fourteen. I supposed therefore that the gentleman must have been Nigel. What was he doing at Spinnaker Farm, if he had really come from the weir bridge? On the other hand, how on earth had he the time to do all the things we want him to have done? All this is very perplexing, and I think I am going to have an interview with Nigel.”

“I thought you said that was impossible.”

“Not now, because I’ve got an introduction. I am going to take back his films, which I found lying about in the fields by the river.”

“And ask him for an explanation of Numbers Five and Six? Miles, dear, that’s much more direct than your methods generally are.”

“Why, no. On the spool I shall give him, Numbers Five and Six will have got fogged somehow. Sort of thing that’s always happening.”

“But they aren’t fogged.”

“Never mind; what man has done man can do. Or woman, anyhow. Your camera takes the same size of film as those, doesn’t it? Very well then, you and I are going to take the car over to Lechlade. Or possibly Cricklade.”

The porch at Lechlade was clearly the porch they wanted; it was a matter of more research to find the identical cinema poster, but fortunately it remained unchanged. “We needn’t worry to fake the thing too carefully,” observed Bredon, “it will be easy to make him believe that he made a mistake.” The whole expedition only occupied some forty minutes; before the hour was up, they were on the river again, looking out for the sight, not uncommon on such a hot afternoon, of cows standing about in shallow water. For the sake of appearances, they paddled up a little beyond Shipcote Lock, returning there for tea. It was hardly to be expected that Mr. Burgess would be posing again for his portrait, and it was necessary for Bredon to understudy the part. Numbers Five and Six on the new film were exposed with the camera tilted up in the air, and the fake reel was complete. Angela had made some photographic purchases in Lechlade, and the films were developed, successfully enough, the same evening.

“They’ve all come out splendidly,” she announced, as she returned, wiping her hands, from the improvised darkroom. “There’s one thing, though. If it wasn’t Nigel who took those photographs, won’t he be a bit surprised at your assuming that it was? And if it was Nigel who took them, won’t you rather put him on his guard by letting on where it was you found them?”

“I don’t think we need worry very much over that. You see, I shall explain that I found them by accident, and had to develop them in order to get any sort of idea who they belonged to. Nigel may deny all knowledge of them, but he must admit that it was a reasonable guess of mine to suppose they were his, since he was known to have been up the river as far as Lechlade. And of course I shall have to practise a certain economy of truth in explaining where I found them. I shall have to say that I found them lying in a hedge somewhere near Shipcote Station. That won’t tell him which path they were found on; and if I put on a sufficiently stupid air, he won’t suspect that I suspect anything. But I ought to be able to get a little out of him, I think. Archimedes today, Machiavelli tomorrow.”