“I was certainly in high spirits,” Sir Clinton confessed blandly. “I think I’d every right to be. I’d got complete confirmation of my suspicion—though really I didn’t need the confirmatory evidence. Let’s get on with the story. We picked up friend Ernest’s cigar-case there; and I kept it. I had a notion that he hadn’t left it there without some ulterior purpose. And besides, I thought his fingerprints might come in useful some time. We didn’t need them, as it turned out. It was merely a precaution on my part. You see, there was very little to be done with fingerprints on these airguns. It seems friend Ernest had carefully organised a grand airgun shooting competition on the morning of the day he killed his brothers. He’d had the guns passed from hand to hand, so that the fingermarks of nearly everyone were printed on them in addition to his own. Of course, I had the tin box containing the spurious darts. He’d handled that. But I hardly troubled to examine it for fingermarks. I was sure he’d use gloves in touching it.
“Then I found another thing which I half-expected. I’d dropped the hint about Ariadne’s clue and the possibility of an outsider having to resort to something of the kind. Well, Wendover and I found some yards of black thread carefully placed where we couldn’t help seeing it. No black thread was found when the Shandons were murdered. But after I’d dropped that hint in Ernest Shandon’s presence, behold! we get the clue which is meant to suggest an outside murderer. Wasn’t that evidence, on the whole, quite enough to raise some suspicions about him?
“Wendover, I may tell you, thought I treated our friend Ernest rather brutally in our interview after the mythical attack on him. I certainly told Wendover afterwards that I thought Ernest had had a bad half-hour. What I meant, Squire, was the bad half-hour he had when he was laying off his tale to us and wasn’t sure what I thought about it. That was a stiff time for him. As a matter of fact, I took no pains to conceal from friend Ernest that I thought his yarn was a mere pack of lies. I wanted him to feel afraid of me, afraid of what I was getting at in the Whistlefield case. Then, I felt sure, he’d have a shy at knocking me out before I became really dangerous.
“To help on that good work, I arranged to play bridge one night at Whistlefield, so as to let him operate on his own ground. In case of accidents, I had arranged that Ardsley should come over and take charge of the casualty. I’d taken most things into account—I had to—and in case friend Ernest hit anyone else in his flurry, I arranged with Ardsley that the injured person was to ‘die’ nominally; so that friend Ernest might be convinced of the efficacy of the faked darts I’d put into his hands, and might go on to further crimes.
“I needn’t go into that affair. I’m not proud of it. I never intended to risk Miss Hawkhurst in that way. Of course, I knew at once she hadn’t been poisoned with curare. But though I’d done my best to sterilise the faked darts, I was afraid of blood-poisoning setting in. I spent a bad time over it, I can tell you. One can never be sure in a case like that.
“Well, there we were. He’d managed to nip back into the winter-garden before Wendover got after him. He believed Miss Hawkhurst was dead and only Arthur’s life stood between him and the whole of the Shandon-Hawkhurst money. By this time, like all successful mass-murderers, he’d begun to feel a complete contempt for the risk of detection. See Burke and Hare.
“So young Hawkhurst was marked down. And this time, friend Ernest meant to have a perfect alibi. He must have guessed that I suspected his other one; and he’d made up his mind to avert even a shadow of suspicion. He’d stay under my eye at the very time that murder was being done in the Maze; nearly a mile away. That was a masterstroke, I admit.
“He used his cigar-case to bait the trap—got Arthur’s back up very skilfully on the point of cowardice. And beforehand he’d set a booby-trap. He’d fixed the airgun in position to shoot at the right level; and he’d arranged a thread to the trigger. When young Hawkhurst came to the entrance to the Maze he stepped against the thread stretched across the opening; the gun went off; and the dart hit him near the heart. So simple! And then Ernest came down with us; stumbled ‘accidentally’ over the airgun; tore away the thread from the trigger before handing the gun to us. And then he ‘found’ Ariadne’s clue for us—the thread he’d laid down as a blind, to make us think it was a stranger at work, someone operating from the river.”
“He was cleverer than I gave him credit for,” Stenness confessed, rather grudgingly. “I always thought him a dull brute.”
“The contents of Roger Shandon’s will took away my last doubts,” Sir Clinton went on. “Besides that, I’d tested the dart he’d used against Miss Hawkhurst and found it was one of the faked lot stolen from the museum that night. So by then the only question was: ‘What should be done with friend Ernest?’ ”
Sir Clinton paused and lit a fresh cigar before going on to the end of his narrative. When he spoke once more his audience was rather surprised by this theme.
“There’s always a good deal of talk in the newspapers from time to time about ‘unexplained mysteries,’ ‘unsolved crimes,’ ‘police inefficiency,’ and so forth. Now I’ll put a case to you. Suppose you were a detective engaged on some beastly case like the Jack-the-Ripper business. And suppose you discovered in the end that
