“The point is that there was nobody in that room but the dead man. I searched it carefully. There was no place to hide. I looked under the bed and in the closet and in the bathroom.

“Furthermore, nobody could have left by that door. It had been locked by the only key that would lock it, and that key was inside the room. Besides, there were four people in that corridor within seconds after Sir James screamed, and three of them were watching that door from that time until I cut it open.

“The windows were bolted shut from the inside. The glass and the laths in the shutters were solid. The windows look out on a small patio which is a part of the dining area. There were twelve people out there — all sorcerers — who were eating breakfast. None of them saw anything, although their attention was directed to the windows by the scream. Besides, the wall is sheer — a thirty-foot drop without ledges, hand-holds, or toeholds. No exit that way.

“There is no evidence that anyone went into that room or came out of it.

“By the time I had searched the room, the Chief Master-at-Arms and two of his men had arrived. You’ve met Chief Hennely Grayme — big, husky chap with a square face? Yes. Well, I told him to take over, to get a preservation spell cast over the body, and to touch nothing.

“Then I went back out in the hall and herded everybody out of there and into one of the empty rooms down the hall. The manager gave me the key and I told him to go on about his business.

“Commander Lord Ashley was a little impatient. He had already delivered his message to Master Sean and had to report back to the Lord Admiral’s office, so I told him to go ahead. Sir Lyon, Master Sean, Master Netly, Journeyman Lord John Quetzal, and the Dowager Duchess of Cumberland all looked shocked at what they’d seen through the door, and none of them seemed to have much to say.

“ ‘Sir Lyon,’ I said, ‘that room was locked and sealed. Sir James was stabbed at a time when there was no one else in the room. What do you make of it?’

“He stroked his beard for a moment, then said: ‘I understand your question. Yes, on first glance I should say that he was killed by Black Magic. But that is merely a supposition based upon the physical facts. I do not suppose you can detect it yourself, but this hotel is not at present equipped with just the ordinary commercial spells for privacy, to prevent unwarranted use of the clairvoyant Talent. Before the Convention started a special group of six sorcerers went through the entire building reinforcing those spells and adding others. They do not affect precognition, since there is no way to cast a spell into the future, but they prevent anyone from using his clairvoyant Talent to see into another’s room, and they make it very difficult to understand or detect what is going on in someone else’s mind. Before I can state flatly that Sir James was killed by Black Magic I should want further investigation into the facts.’

“ ‘There will be,’ I told him. ‘Next question, then: Who had reason to kill him? Had anyone quarreled with him?’

“So help me, Lord Darcy, every eye in the room turned to Master Sean. Except Master Sean’s, of course.

“Naturally, I asked him what the quarrel was about.

“ ‘It wasn’t a quarrel,’ he said firmly. ‘Both Sir James and I were angry, but not at each other.’

“ ‘Who were you angry with, then?’

“ ‘Not with anyone. We had both been working on a new thaumaturgical effect, and had discovered almost identical spells to produce that effect. It has happened before in the history of magic. We may have been growling and snapping at each other, but we weren’t angry at anything but the coincidence.’

“ ‘How did the… er… discussion come about? I asked him.

“ ‘Chance conversation in the committee room. We fell to talking and the subject came up. We compared notes, and… well, there it was. What we were really arguing about was who was to present his paper first. So we called Sir Lyon over to decide the problem.’

“I looked at Sir Lyon. He nodded. ‘That’s correct. I decided that it would be best for them to pool their findings and present the paper jointly, under both their names, with a full explanation that the work had been done by both independently.’

“ ‘Tell me, Sir Lyon,’ I said, ‘this paper — or these papers — wouldn’t be just a lot of thaumaturgical equations, would they?’

“ ‘Oh, no. They would have a full exposition of the effect. There would be equations, of course, but the text would be in Anglo-French. Naturally, there would be a lot of technical words, professional jargon, if you will, but—’

“ ‘Where is Sir James’ paper, then? I asked. ‘It isn’t in his room.’

“ ‘I have it,’ said Sean. ‘It was agreed between Sir James and myself that I should do a first collation between the two papers, and then we’d talk the thing over this morning at nine-thirty and do a second draft of our collaboration.’

“ ‘When was the last time you saw Sir James?’ I asked.

“ ‘Last evening at about ten, it was,’ Sean explained. ‘I went with him to his room, so he could give me his manuscript. So far as I know, that’s the last anyone saw of him. He was going to do a little further work he had in mind, and he didn’t want to be disturbed until half past nine.’

“ ‘Would he have been using a knife for that work?’

“ ‘Knife?’ he said, looking puzzled.

“ ‘You know. One of those big, black-handled silver knives.’

“Oh. You mean a contact cutter. I wouldn’t think so; he said he wanted to do some paper work, is all. Not any actual experimentation. Still, I suppose it’s possible.’

“I said, ‘Master Sean, do you mind if I take a look at Sir James’ manuscript?’

“I guess that must have fired his Irish temper up. ‘I don’t see what that has to do with this business,’ he said peevishly. ‘I’ve been working on this thing for three years. It was bad enough that Sir James was doing the same thing, but I’m not going to let out this information until I’m ready to present it myself!’

“Then Grand Master Sir Lyon spoke. ‘I cannot insist that you show those papers to the Chief Investigator, Master Sean; I cannot ask you to reveal the process. But I feel that the subject may possibly have a bearing on the case.’

“Master Sean opened his mouth and then closed it again. After a second or so, he said: ‘Well, that’s already on the Program anyway. My paper was to have been called “A Method of Performing Surgery Upon Inaccessible Organs.” Sir James called his “The Surgical Incision of Internal Organs Without Breaching the Abdominal Wall.” ’

“That was when Master Netly squeaked, ‘You mean a method of controlling a blade within an enclosed space? Astounding!’ Then he backed away from Sean a couple of steps. ‘That’s what he meant when he screamed!’

“That was the first I’d heard that Master Sir James had actually screamed words. The words were — and they all agreed on it -

“ ‘Master Sean! Help!’ ”

The Marquis of London had been sitting during the entire narration with his eyes closed, but he was not asleep. “Satisfactory,” he said. Then he opened his eyes, looking at Lord Darcy. “Now,” he rumbled, “you understand why I felt constrained to order the arrest of Master Sean O Lochlainn on suspicion of murder.”