“The Photoflood bulb gave it away. Already, in a musing, curious, but entirely perplexed way, I had been asking questions about those bulbs. What intrigued me was the report I had heard of Miss Wills’s obvious astonishment when she was told that the bulb had burned out. Why should she have been astonished? The question, possibly, was of no importance; but it is just that sort of wrongness which presses the button when a door is obstinately stuck. Now, she bought the bulb that morning. It was not called into use until that night. How long had it been in use that night?
“That was easy enough to determine. Chesney’s show started (roughly) about five minutes past twelve. The bulb was turned on. It was left burning until the police arrived at twenty-five minutes past twelve at which time (do you recall?) it was turned out. That’s twenty minutes to start with. It was turned on again, very briefly, when the police had a short look at the room before they were interrupted by you, Professor Ingram. Out it went again, after a period of a very few minutes: less than five, anyhow. The third and final time it was turned on was when the police-surgeon and the photographer arrived. There again the period was brief, just long enough for Elliot to explain to Major Crow about a spring-grip bag, and for them to make an examination of the clock on the mantelpiece; then it burned out. Say five minutes more.
“Even agreeing that all these times are approximate, still there’s too great a discrepancy. That bulb has burned out after a total of only half an hour’s use altogether. For Stevenson the chemist assured me that bulbs would burn for well over the full hour.
“It burned out after half an hour’s use because somebody had been using it before, earlier in that same day.
“That simple fact stared me in the face when I found the cardboard container in the drawer. Miss Wills had bought the bulb that morning, and put it into the drawer.
She
hadn’t used it afterwards, because we heard from the maids that she went over to Professor Ingram’s house in the morning and stayed there until late afternoon; and, in any case, we have had impressed on us over and over that she never dabbles with photography.
“We were supposed to believe, in fact, that nobody had used it up to the time Pamela was sent upstairs to fetch the bulb at a quarter to twelve that night. But as I have just indicated, this couldn’t be so. And it was emphasized by another reason. We found the cardboard container. Now, if Pamela had been told to go upstairs and get the bulb, and the bulb was still sealed into its box, she would have brought it down box and all. But she didn’t: she brought the bulb alone. Which meant that the container had been already opened, which meant either that the bulb was lying loose in the drawer or stuck back into an open box.
“It had already been plain, I grant you, that Chesney, Emmet, and Harding must have had long careful rehearsing for this little show. The thing had to go without a hitch. And the question was, when did they do the rehearsing? Clearly that afternoon. Chesney had got the bulb bought that morning. Miss Wills was absent in the afternoon; and since you, Dr. Chesney, do not live here anyway, there was no reason why you should be here. But Harding was here right enough: we heard that from the maid.
“You now perceive the nature of Chesney’s final trick and joke, his last hoax for the witnesses. He was going to deceive you even after all possible deception had ended. By having Harding take a film of the show in advance—
a show which in several subtle points should be completely different from the real one
—he would keep an ace up his sleeve. He would say, ‘Well, you have made your replies. Now see what really happened. The camera cannot lie.’ But the camera could lie; for it was Emmet who played Dr. Nemo’s part, and the words Chesney spoke were totally different though the number of syllables was approximately the same. I darkly believe that this fraud was intended for my benefit. In a few days, you know, he was going to invite me over to see his show. Then he would say to me as well, ‘Now look at a film we took of it the other night.’ And (presumably) I should have been gulled as well, while all the time he, uproariously amused, should be saying from the screen, ‘I do not like you, Doctor Fell.’ He almost admits as much in his letter. ‘Show them a black-and-white record of it afterwards, and they will believe you; but even then they will be unable to interpret correctly what they see.’
“Changing those films on us was George Harding’s one great, smashing mistake. There were, of course, duplicate cameras. He let Emmet take the film with one camera; he gently handed us the other camera with the other record. It will probably soothe you to learn that Bostwick has found the other camera hidden in his room, with the film miraculously undestroyed; and that little bit of pure conceit is going to hang him.
“But the solution of the two films provided our last answer and drove in the last nail. For a long time I had been wondering dimly: was the fact that George Harding took the picture from so far to the left
only
an indication that he wanted to be close to the windows? And here was still another reason. He wasn’t placed so that he could film the window of the office, through which Nemo appeared, because he didn’t dare film it. It would have shown the afternoon sunlight—when he took the rehearsal-film—blazing in at the windows as Nemo entered. The windows of the office face west, and yesterday was a day of brilliant sunshine. So he had to stand at one side; and, in the same way, Emmet had to stand at one side for the evening performance. When Inspector Elliot suddenly realised what was happening from my questions about the Photoflood bulb, he also hit on the meaning of what we may call the Left-handed Photographic Stance; and a picture of the truth appeared plain and clear on the wall.”
Elliot grunted. Dr. Fell, whose pipe had gone out, drained his tankard of beer.
“Now let us sum up the rather painful business of George Harding and Marjorie Wills.
“Harding planned a series of clever and savagely cold-blooded crimes some months ago for just one motive: Financial gain. He meant to show first off that, whoever the poisoner at Sodbury Cross might be, it could not possibly be George Harding. His method of attack was not new. It had been tried before. All along you have been quoting the case of Christiana Edmunds in 1871. I told Elliot there was a moral in that story; but some of you have discussed the case and persistently refused to see the moral. The moral is not: beware of women who run after doctors. The moral is: beware of the person who may poison innocent people at random merely to show he could not have been the poisoner. That is what Christiana Edmunds did; and it is what George Harding did.
“In his fat-witted vanity, a vanity comparable to Palmer’s or Pritchard’s, he believed he could do exactly as he pleased with Marjorie Wills. I grant you he had reason to think so. A woman who pays your expenses for a several months’ holiday may fairly be described as indulgent or even doting; and, if it is any consolation to him, he will be the legal husband of a rich woman until the hangman turns him loose into other pastures.
“Marcus Chesney was a very rich man, and Miss Wills was his heiress. But until Chesney (a tough-fibred man in every sense of the word)—until Chesney died, Harding could hardly hope for a penny. He knew that all along, and I understand Chesney made it very clear to him. Harding really did want to launch his new electro-plating process along large lines, and for all I know it may be a very fine process, though it is a different sort of electrical treatment I should like to see applied to him. He thought himself a great man who had to have it, so Marcus Chesney must be eliminated.
“He was thinking along these lines, I suspect, from the very time he met Marjorie. He therefore ‘planted’ a poisoner at Sodbury Cross along the lines you know. One visit to Mrs. Terry’s shop, in any sort of disguise, would give him the layout and the position of the chocolate-boxes; a visit a few days later would enable him to switch the boxes. He used strychnine for a deliberate reason—because it is one of the few poisons a research chemist does
not
deal with. Where he bought it we don’t yet know, but it is hardly a wonder the police failed to trace it: they had never heard of George Harding.”
“Thanks,” said Major Crow.
“Nor do we know what his original scheme was for eliminating Chesney. But bang into his lap, a gift from heaven, dropped this opportunity to poison Chesney with his victim’s actual encouragement and co-operation. Also, Chesney had tumbled to the trick with the chocolate-boxes; and Harding had to make haste. Ironically, Chesney never for an instant suspected Harding’s guilt. But he must not go on too far with his investigations, or he might uncover too much. Now, one thing rather worried Harding. If he were to carry out the murder in that way, he had to use a poison which struck and killed almost instantly. That meant that it had to be one of the cyanides; he was working with potassium cyanide; and suspicion would instantly be directed at him.
“He got round it with a great dexterity of acting. I said this afternoon that I was sorry to tell you Harding had obtained no poison from his laboratory. He hadn’t. He manufactured it here. This house, as you have noticed, and particularly the grounds round-about, are both haunted by a faint odor of bitter-almonds. The one difficulty about concealing prussic acid anywhere is its faint smell even when corked down; but this smell would never be noticed at Bellegarde unless somebody got a deep whiff from the opened bottle. So he manufactured his prussic acid, and he deliberately left some of it in the bathroom cabinet. He did this so that he could point out to you how easy it was for anybody with a small knowledge of chemistry to make prussic acid, and that someone was trying to throw suspicion on him. I have no doubt he made a good story of it.”
“He did,” said Major Crow.
“I do not think he had any idea, at the beginning, of trying to throw suspicion on Marjorie. That would have been foolish and dangerous. He might want the girl’s money, but he certainly didn’t want the girl arrested. He only tried to throw suspicion on Wilbur Emmet by planting the cardboard pill-box in Emmet’s pocket. Chance, however, threw heavy suspicion on Marjorie, and Harding saw a way of using it to his own advantage. For he was getting a bit alarmed over something else: the girl was cooling off.
“You all noticed that. For some weeks her ardour had been definitely on the wane. She no longer looked with bedazed eyes at her charmer; she had got, perhaps, a glimpse or two into his soul; she had a tendency to snap at him, she even considered suicide. Harding, even in the fullness of his vanity, could not help dimly suspecting something like this. He couldn’t lose her now, or he would have run several horrible risks for nothing, and that was bad business. The sooner he could stampede her into marriage, the better for him.
“He did it by a combination of tenderness and terrorisation. The murder of Wilbur Emmet, a necessary part of his plan, he committed with a hypodermic stolen from you, Dr. Chesney. And the next day he planted it in the false bottom of the jewel-casket. The girl was already half mad with fear; and Harding, missing no opportunity, had got her into such a state that she was willing to cling to him for the pure and insane relief of letting someone carry her troubles. That last effort, with the hypodermic, did the trick. She told us herself she got married to avoid being arrested for murder. I have no doubt Harding pointed out many things to her; among them, that the police might uncover her visits to the laboratory and find she had access to poison; but if she were arrested, and they were married, he would not have to testify against her in the witness-box. Gentlemen, when you stop to consider the smooth, the calm, the complete eye-dazzling cheek of an approach like that——”
Dr. Fell paused, with a guilty kind of start; Major Crow hissed at him; and then they all stared steadily, and with a furious embarrassment, at the fire.
Marjorie had come in.
Elliot would not have imagined that she could look so pale or that her eyes could acquire such a glitter. But her hands were steady.
“It’s all right,” Marjorie said. “Please go on. You see, I’ve been listening at the door for five minutes. I want to hear.”
“Hrr!” said Major Crow. He bounced out of his chair, and began to fuss. “Would you like a window open? Or a cigarette? Or a brandy? Or something?”
“Have this pillow,” urged Dr. Chesney earnestly.
“I think, my dear, that if you were to lie down—” began Professor Ingram.
She smiled at them.
“I’m quite all right,” she said. “I’m not nearly as brittle as you think. And Dr. Fell is quite right. He
did
do all that. He even took the books on chemistry I’ve got upstairs in my room, and used them against me. I got them, you know, so that I could read up and try to take an intelligent interest in the work he was doing; but he said what would the police think when they found them there? What’s more, he—he knew what Inspector Elliot knew: about my trying to buy potassium cyanide in London——”
“What?”
roared Major Crow.
“Didn’t you know?” She stared at him. “B-but the Inspector said—at least, he hinted——”
This time Elliot’s face was so hot that there was no mistaking it in anyone’s eyes.
“I see,” Major Crow remarked politely. “Let it pass.”
“A-and he even said they might suspect me of having something to do with the show where Uncle Marcus was killed. He said he knew Uncle Marcus had written a letter to Dr. Fell, and the letter said to keep an eye on my actions.…”
“It did,” said Dr. Fell. “‘I will be fair and give you a straight tip: keep a close eye on my niece Marjorie.’ That is why I so carefully kept the letter away from the impressionable Superintendent Bostwick until I could show who was really guilty; it would only have led him in the wrong direction. Your uncle was trying to gull me in the same way he tried to gull you by saying Dr. Nemo was Wilbur Emmet. But the effect on Bostwick——”
“Please wait,” the girl urged, clenching her hands. “You don’t need to think you can make me faint by telling me the truth. When I saw George this afternoon, I mean when he thought he’d been shot, I was so utterly disgusted that I felt sick. But that’s what I wanted to know. Was it an accident that he got shot?”