“Ordinarily, when a man charged with murder tells you he is guilty you can form a pretty good guess between the two obvious alternatives — either he is telling the truth or he ought to be in an asylum. Occasionally there is a third possibility, for which the present circumstances did not seem to leave any room: he may be inculpating himself to save somebody else. I tell you, I didn’t know what to make of it. The whole story seemed wrong; Westmacott was not a strong man, and what would he have done if his man had not been asleep? The chances are enormously against most men sleeping soundly on a train.
“Now, what was I to do? I felt certain the man was not mad, and I have seen many lunatics in my time. I did not, could not, believe he was really guilty. I put it to you whether, with those convictions in my mind, I was not really offering to serve the cause of truth when I urged him (as of course I did) to plead ‘Not guilty.’
“He would have none of it — then. It was only a day or two later that I had an impassioned appeal to go and see him again. I found his mind entirely altered. He still stuck to his story that Robinson had been blackmailing him, but he professed to know nothing whatever about the disappearance: he thought Robinson must have either committed suicide or else staged a very clever disappearance with the sole intention of bringing him, Westmacott, to the dock. He implored me to save him from the gallows. This was too much for me; I couldn’t undertake to plead for a man who didn’t know from one day to the next whether he was guilty or not guilty, and gave such very lame explanations of his movements and his motives in either case. At last, when I had been at him some time, he told me a third story, which was quite different, and, as I believe, true. I shan’t tell you what it was just yet. As I say, I thought, and think, it was true. But it was obvious to me from the first that it was a story you could not possibly serve up to a jury.
“There was another odd thing, which was that now, for reasons you will understand later, I did not know whether I wanted my man hanged or not. I don’t know how some of you severe moralists would have formed your consciences in a situation like that. I thanked God I could fall hack on a legal tradition, and I resolved that I would defend Westmacott, devoting myself single-heartedly to pointing out the weaknesses in the story, whatever it was, the prosecution would bring against him. And, gentlemen, I succeeded. I don’t think I have ever had a tougher fight; there was any amount of prejudice against him among the public at large, and the jury, as usual, reflected it. But there was the solid fact that no body had been found; the open possibility that Robinson had made away with himself, or slipped off somehow when the train stopped. And, of course, the difficulty of throwing a body clear of the bridge. There was a mass of circumstantial evidence, but not a line of direct proof. Of course, you see what had happened.”
McBride, who had been sitting with his head buried in his hands, lifted it slowly. “I expect I’m being a fool,” he said, “but I don’t believe there was any such person as Robinson. He was just Westmacott, wasn’t he?”
“That’s a theory to go on, at all events,” admitted Sir Leonard, accepting the whisky-and-soda with which the suggestion was accompanied. “Let’s hear your reasons for thinking that, and I’ll put the difficulties.”
“Well, as you’ve told the story, nobody ever saw the two men together. When Robinson was seen going out of the house, it was supposed to be Westmacott who had let him in. At the station, there was nothing to prevent Westmacott getting out of his sleeper during that last quarter of an hour, going off somewhere, and putting on the Robinson disguise, picking up fresh luggage at the cloakroom, and so making his second appearance. He made sure that the attendant should see him at Dalmeny, because he wanted everybody to think that Robinson had been thrown overboard exactly at the Forth Bridge. There was no point in making the body disappear when all the circumstances would, in any case, point to murder — unless there was no body to disappear.”
“Good for you, McBride; I like to hear a man put a case well. And now let me point out the difficulties. You’ve got to suppose that a man who has already labored under an awkward imputation of intended murder deliberately projects an alter ego — a sort of Mr. Hyde — for no better purpose than to get rid of his imaginary carcass, thereby letting himself in for a second dose of suspicion. That, having done so, he first of all pretends to his counsel that he is really a murderer, and then he withdraws it all and decides to plead ‘Not guilty.’ Can you give a coherent explanation?”
“The man was balmy,” suggested Penkridge.
“Who isn’t, up to a point? But there was certainly method in poor Westmacott’s madness. Shall I tell you the story he told me?”
“We’ll buy it!” agreed Penkridge.
“I wonder if you could have guessed it? If so, your guesswork would have had to start from the moment at which, if you remember, Westmacott suddenly came home one day a changed man, with the shadow of something over his life. You see, he had been feeling ill for some time. He had made an appointment with a specialist, and that specialist told him the worst he had been afraid of hearing. Not only were his days numbered, but he must look forward to months of increasing pain, during which, very probably, his reason would be affected. That is the whole story; the rest just flows from it.
“Westmacott hated pain, perhaps more than most of us. He was not capable of facing great endurance, whether in action or in suffering. It didn’t take him long to realize that there was only one thing for him to do — to cut his life short by suicide. He went out and bought a revolver with the necessary ammunition. He shut himself up with it, and found that his hand was that of a physical coward; it would not pull the trigger. He tried long-distance methods, bought some poison, and tried to dose himself with it. Even here he had no better success. He realized, with self-loathing, that he was a man who could not take his own life.
“It is open to you to say, if you like, that something went wrong with his brain after that, but if he had the makings of a lunatic, his was the logic of lunacy. If he could not kill himself, he must make somebody else do it for him. He had not the physique to embark on some arduous adventure: fighting, for example, or a difficult mountain climb. Bravoes cannot be hired nowadays. There was only one way he could think of inducing somebody else to kill him — and that was to hill somebody else! He must get himself condemned to the gallows.
“Well, as you see, he went about that in a painstaking way. He deliberately went and stayed at that appalling hotel because he knew that he would meet there the sort of people he most disliked. He found himself in luck; Smith was there, and Smith was a man who, in his view, would be all the better for extermination. Circumstances favored him, too, in showing him a way to achieve his end. With all that reading of detective stories, you see, he had become fantastically ingenious in his conceptions of crime. He laid a trap for his victim which would make it possible for him to effect the murder by merely turning a tap, and then turning it a second time. There would be no blood, no struggle, no circumstances of violence.