"But I've told you already I ..."
"Colin, I haven't got much time. Listen. David went with you. Mrs. Lefroy remembers seeing you both come in together. And," said Roger with emphasis, "David himself remembers that he went in with you. David himself remembers it, Colin."
"Oh!" said Colin slowly.
"Yes, you were wrong, I'm afraid. But the lad's perfectly safe, so long as you remember just that thing."
"Of course I remember we went in together, said Colin firmly. "Haven't I told you so all along?"
"Then thank goodness that's settled." Roger mopped his brow and took a breath of relief.
"But, Roger, man, what are the police up to? Do you mean to tell me they smell a rat? What were they doing, taking photographs on the roof?"
"I don't know," Roger admitted. "But that appears to be my next job, to find out. Little did I think that the Great Detective would ever come down to detecting what the official detectives may have detected already. Well, well."
"Does it look serious, do you think?"
"No, I don't think so really," Roger said, as they walked back towards the house. "It's alarming, of course, but I don't see how it can possibly be serious. They can't have anything more than the vaguest suspicions; and suspicion never even arrested anyone without some kind of evidence, too, let alone hanged him. Anyhow, if the coast's clear we'll see if we can make out what they've been up to."
The coast was clear and the roof unguarded. Even the large constable had been withdrawn. "Ah!" said Roger and looked round. At a first glance everything seemed exactly the same. "Well, I don't know what the deuce they were at, unless they really were still worried about that chair," said Roger and walked towards the gallows.
"Hullo!" he exclaimed in surprise. "It's gone!" He looked round again. Undoubtedly the chair was gone. Three chairs still stood on the roof, but exactly as they had stood before. The fourth, under the gallows, had disappeared.
"Let's see if it's in the sun parlour," said Roger. It was not in the sun parlour. "Well, what on earth would they want to take it away for?" asked Colin, no less puzzled.
"Heaven only knows." Roger was beginning to feel worried, in the way that the inexplicable does worry. "I can't make it out at all. The only importance in the chair to them was its position with regard to the gallows. As an object apart from its position, I can't see how it could possibly interest them." Already such a simple act as the carrying away of the chair was beginning to look sinister. Roger felt perfectly equal to combating the known moves of an opponent, but this was an unknown one, and how can one combat that?
"Ach," Colin tried to be reassuring, "they're just daft. Trying to be too clever, that's all."
"No," Roger worried. "No, I don't think that can be it. They must have had some reason." He stared at the roof where the chair had lain. Suddenly he uttered an exclamation and dropped on his hands and knees, to peer intently at that same bit of roof.
"Have you found something?" Colin asked eagerly.
Roger blew gently at the ground, and then again. Then he got up and faced Colin. "I know why they took that chair away," he said slowly. "Colin, I'm afraid we're rather up against it."
"What do you mean, man?"
"I was wrong when I said they were working just on suspicion, with no evidence to back it. They have got evidence. Can you see faint traces of grey powder there? That's insufflator powder. They've been trying to take fingerprints off that chair, and they've found that there aren't any at all - not even Ena's."
CHAPTER XII
UNSCRUPULOUS BEHAVIOUR OF A GREAT DETECTIVE
"WE MUST keep calm," said Roger, not at all calmly. "We mustn't lose our heads. We're in a nasty jam, but we must keep calm, Colin."
"It's the devil," muttered Colin, in a distressed voice.
"We must try to work out their moves," Roger continued, a little less wildly, "so that we can forestall them. You're the only person I can talk to freely, so you've got to help me."
"I'm with you all the way, Roger."
"You'd better be," said Roger grimly. "Because we're both of us for it if the truth comes out. In a moment of lunacy I put myself in the position of accessory after the fact, to shield someone else (I suppose one can be an accessory after the fact to a crime, by the way, without having the least knowledge of the criminal's identity? It's an interesting point); and you did the same by shielding me. I hope you realize that?"
"I'm afraid you're right. I'm an accessory to an accessory at any rate, if there is such a position. But let's look on the bright side, Roger. Things might have been worse if I hadn't wiped those prints of yours off the chair. Worse for you, I mean."
"And possibly worse still for someone else besides me," Roger retorted.
The two were sitting in the sun parlour, whither they had retired in some alarm, after Roger's discovery on the roof, to talk the thing over. Roger had spent another five minutes crawling about on his hands and knees round the gallows, to see whether anything else was to be read from the surface of the roof, but beyond one or two burnt matchstalks had found nothing. He had explained to Colin that the police would have done exactly the same thing, and equally, it was to be presumed, found no scratches or other marks on the surface of the asphalt to indicate that anything in the nature of a struggle had taken place there; though whether they might have found anything else, of a removable nature, could not be said.
Roger relit his pipe and continued, considerably calmer. Unlike many people, Roger found argument soothing.
"Yes, that's quite true, Colin," he said. "If you hadn't wiped off my prints, what would they have found? That officious inspector was going to test the chair for prints in any case. He'd have found mine and presumably those of the person who carried all the chairs onto the roof, and probably several others as well. But he wouldn't have found Ena Stratton's, which he was looking for; and that might have made things more awkward even than they are now. I wonder, by the way," Roger added vaguely, "how the particular chair of the four which I chose happened to get where it was, right in the middle of the fairway. It was the one, of course, which you knocked over."
"I didn't knock it over," Colin contradicted. "It nearly knocked me over. It was lying on its side. That's why I didn't see it."
"Lying on its side, just about halfway between the gallows and the door into the house," Roger meditated. "It might have been there, of course, when I was standing just outside the door earlier, but if so I don't remember noticing it. And it certainly wasn't there at the beginning of the evening, when Ronald took me up to show me his gallows, because we walked abreast straight across from the door. Somebody must have put it there later. I wonder if that has any significance?"
"Well, there was a chair missing from the picture," Colin pointed out.
"Exactly. Could the murderer have been going towards the gallows with it, intending to complete the picture, and then been alarmed or distracted, and dropped it there to make his escape?"
"That sounds feasible enough, Roger."
"Yes, but it's so easy to think of a feasible explanation of a fact, without knowing in the least whether it's the right one, and probably without realizing how many other feasible explanations of the same fact there may be. That was the trouble with the old - fashioned detective story," said Roger, somewhat didactically. "One deduction only was drawn from each fact, and it was invariably the right deduction. The Great Detectives of the past certainly had luck. In real life one can draw a hundred plausible deductions from one fact, and they're all equally wrong. However, we've no time to bother with that now."