The colonel was saying something about an unfortunate incident that had happened some years ago in Sarawak. I waited until he slowed down for a semicolon, then said, “Excuse me.”

The room went still.

“I’m afraid you ought to call the police right away,” I said. “I think they’ll want to get here just as soon as they can, no matter how deep the snow is.”

“What are you saying, Mr. Rhodenbarr?”

I turned to Molly Cobbett. “When you came in here this morning,” I said pleasantly, “just what did you do?”

“I never touched him, sir! I swear to God!”

“I’m sure you didn’t,” I said. “I believe you said you opened the drapes.”

“Sure I did, sir. I’m always to draw them open in the daytime, so as to let the light in.”

“And was the room dark before you drew them?”

“It was, sir. Not full dark, as some light came in through the open door, from the other room, like.”

“But there were no lights on in this room,” I said.

“No, sir.”

“No lamps lit.”

“No, sir.”

“And there was a little light from the open door,” I said, “because dawn was breaking. But earlier, when Mr. Rathburn had his tragic accident, it would have been full dark, wouldn’t it?”

She looked at me. “I wasn’t here, sir.”

“Of course you weren’t,” I agreed. “But if you had been, and it wasn’t dawn yet and there were no lamps turned on and the drapes were drawn shut, you’d have found the room dark, don’t you suppose?”

Molly stood openmouthed, thinking about it. Nigel Eglantine frowned in thought, looking reluctant to take the thought the next step down the trail. His wife said, “Why yes, of course. It would have been pitch dark in here when Mr. Rathburn fell.”

“That might explain his stepping on his shoelace,” I said. “He wouldn’t have seen it had come untied. But what it doesn’t explain is why he’d be up on the steps in the first place. It would have been far too dark in here for him to find the steps, let alone pick out a book to read.”

Blount-Buller cleared his throat. “What are you saying, Rhodenbarr?”

“I’m saying it’s more complicated than it looks. Jonathan Rathburn would not have had an accident of this sort in a dark room. Either a light was on when he fell or what took place was rather different from your reconstruction of it.”

Cissy Eglantine said, “Molly, are you sure you didn’t turn off a lamp?”

“I don’t remember,” the girl wailed. “I don’t think I did, but-”

“It doesn’t seem likely,” I said. “The room was dark when she entered it. If there had been a light burning, she’d have noticed it. If she didn’t notice it, how would she happen to turn it off?”

“We don’t know what step he was standing on,” Gordon Wolpert observed. “But suppose he was mounted on one of the top steps. That would be quite a tumble, enough to give him that cut on his head and knock him cold. Might he not have landed with sufficient impact to extinguish a lamp?”

“If he fell on the lamp,” I said, “then it would certainly be possible. Or even if he didn’t, assuming he landed so hard that a floor lamp was overturned, or a table lamp sent crashing to the floor.” Another possibility occurred to me. “Bulbs burn out,” I said. “Of their own accord. It’s not inconceivable that a bulb was lit when he had his accident and burned out before Molly found him.”

“That must be what happened,” Nigel Eglantine said.

“In that case,” I said, “it’s still burned out, because I think we can all agree that Molly hasn’t had a chance to replace it yet. Could we try all the lamps and light fixtures?”

“All of them?”

“All of them. A burned-out bulb won’t prove the theory, but the lack of one will rule it out.”

As indeed it did. Every bulb worked, and once we’d established as much I had them switch the lights off again. We didn’t need them; with the whole world outside snow-covered, more than enough light was reflected through the wall of windows.

“Well,” I said.

It was a choice moment. They were all looking my way, waiting for me to say something, and the phrase that came unbidden to my lips was I suppose you’re wondering why I summoned you all here. It’s a sentence I’ve had occasion to utter in the past, and the words have never failed to set my own pulse racing with the thrill of the hunt. But this time they weren’t really appropriate. I hadn’t summoned anyone, nor had they cause to wonder why they were here.

I was stuck for le mot juste. Cissy Eglantine helped me out.

“There must be an explanation,” she said.

“I can think of one,” I allowed. “Rathburn had a light on when he climbed the library steps and had his accident. He fell like Bishop Berkeley’s tree, without making a sound, so no one came running. But sometime afterward someone else passed the room and saw the light on. He or she realized the light shouldn’t be on, not in the middle of the night, and came in to turn it out. If it was this lamp, say, or that one, he or she couldn’t have missed seeing Rathburn’s body, because it would have been right in his or her line of sight. Damn it all, anyway.”

“What’s the matter, Bern?”

“He or she,” I said. “His or her. If nobody objects, I’m just going to use the masculine pronouns from here on.” Nobody objected. “Good,” I said. “The point is, there are other lamps that could have been lit that a passerby could have turned off without ever coming into line of sight of Jonathan Rathburn’s body. He could have walked in, turned off the light, and left the room without the slightest idea there was a corpse on the floor.”

A murmur approved this line of thought. Even as it died down, Gordon Wolpert cleared his throat. “I wonder,” he said. “Would you turn out a light in the library without taking a look to make sure there was nobody curled up in a chair with a good book? I should think simple manners would demand it.”

“Good point,” I said.

“And when you looked round, you’d almost certainly see Rathburn.”

“If you actually looked,” Carolyn said. “But you might just call out, ‘I say, anybody here?’ And, unless Rathburn managed to say something, you’d figure you had the room all to yourself.”

Wolpert thought that made sense, and no one else offered any objection. “Fine,” I said. “So there’s only one question left to answer. Who turned off the light?”

No answer.

“It would have to have been one of us,” I said, “and I don’t think it’s the sort of thing we’d be likely to forget having done. Did anybody here come in late last night or early this morning and switch a light out? Any of you?”

They looked at me, they looked at each other, they looked at the floor. Leona Savage whispered discreetly to her daughter, and Millicent piped up to deny that she’d even been to the library at the time in question, let alone turned out any lights. Her father supported her claim, pointing out that the child had never voluntarily turned out a light in her life.

“It seems no one turned off the light,” Colonel Blount-Buller said. “So it would appear we’re left with two possibilities. Rathburn climbed the stairs in the dark or the light went out of its own accord.”

“Neither of which makes any sense,” I said. “Here’s another-someone did turn off the light, but he can’t admit to it because he can’t let us know he was anywhere near this room last night. Because he murdered Rathburn, and he turned off the light to delay discovery of the body, never considering how suspicious it would look for Rathburn to be found in a darkened room.”

“But that’s plainly impossible,” Nigel Eglantine said.

“Why?”

“Because it would mean…”

“Yes?”

“That someone in this house committed murder,” he said.

“I’m afraid so,” I said.

“But none of us…”

“Not one of us,” Cissy Eglantine said stoutly. “If anyone actually did harm poor Mr. Rathburn, there’s no way on earth it could have been one of us.”