“Very good, my lord. Would you want any other tests besides the usual ones?”

“Yes. First: Was there, in fact, anyone at all in this room when Sir James Zwinge died? Second: If there was any black magical effect directed at this room, of what sort was it?”

“I shall endeavor to give satisfaction, my lord,” Master Sean said doubtfully, “but it won’t be easy.”

Lord Bontriomphe rose to his feet and handed Master Sean the magnifying glass. “What would be difficult about it?” he asked. “I know those tests aren’t exactly routine, but I’ve seen journeyman sorcerers perform them.”

“My dear Bontriomphe,” said Lord Darcy, “consider the circumstances. If, as we assume, this act of murder was committed by a magician, then he was most certainly a master magician. Knowing, as he must have, that this hotel abounds in master magicians, he would have taken every precaution to cover his tracks and hide his identity — precautions that no ordinary criminal would ever think of and could not take even if he had thought of them. Since Master Sir James was killed rather early yesterday morning, it is likely that the murderer had all of the preceding night for the casting of his spells. Can we, then, expect Master Sean to unravel in a few moments what another master may have taken all night to accomplish?”

He put his hand into an inside jacket pocket and took out the envelope which de London had handed him earlier. “Besides, I have further evidence that the killer or killers are quite capable of covering their tracks. This morning’s communication from Sir Eliot Meredith, my Chief Assistant, is a report of what he has thus far discovered in regard to the murder of the double agent Georges Barbour in Cherbourg. It contains two apparently conflicting pieces of information.” He looked at Master Sean.

“My good Sean. Would you give me your professional opinion of the journeyman who is the forensic sorcerer for Chief Master-at-Arms Henri Vert in Cherbourg?”

“Goodman Juseppy?” Master Sean pursed his lips, then said: “Competent, I should say; quite competent. He’s not a Master, of course, but—”

“Would you consider him capable of bungling the two tests which I have just asked you to perform?”

“We are all capable of error, my lord. But… no. In an ordinary case, I should say that Goodman Juseppy’s testimony as to his results would be quite reliable.”

“In an ordinary case. Just so. But what if he were pitted against the machinations of a Master Sorcerer?”

Master Sean shrugged. “Then it’s certainly possible that his results might be in error. Goodman Juseppy simply isn’t of that caliber.”

“Then that may account for the conflicting evidence,” Lord Darcy said. “I hesitate to say definitely that it does, but it may.”

“All right,” said Lord Bontriomphe impatiently, “just what is this conflicting evidence?”

“According to Goodman Juseppy’s official report, there was no one in Barbour’s room at the time he was killed. Furthermore, there had not been anyone but himself in the room for several hours before.”

“Very well,” said Lord Bontriomphe, “but where is the conflict?”

“The second test,” said Lord Darcy calmly. “Goodman Juseppy could detect no trace whatever of black magic — or, indeed, of any kind of sorcery at all.”

In the silence that followed, Lord Darcy returned the envelope to his jacket pocket.

Master Sean O Lochlainn sighed. “Well, my lords, I’ll perform the tests. However, I should like to call in another sorcerer to help. That way—”

“No!” Lord Darcy interrupted firmly. “Under no circumstances! As of this moment, Master Sean, you are the only sorcerer in this world in whom I can unhesitatingly place complete trust.”

The little Irish sorcerer turned, took a deep breath, and looked up into Lord Darcy’s eyes. “My lord,” he said in a low, solemn voice, “in all humility I wish to point out that while yours is undoubtedly the finest deductive mind upon the face of this Earth, I am a Master Sorcerer.” He paused. “We have worked together for a long time, my lord. During that time I have used sorcery to discover the facts, and you have taken those facts and made a cogent case of them. You cannot do the one, my lord, and I cannot do the other. Thus far there has been a tacit agreement between us, my lord, that I do not attempt to do your job, and you do not attempt to do mine. Has that agreement been abrogated?”

Lord Darcy was silent for a moment, trying to put his thoughts into words. Then, in a startlingly similar low voice, he said: “Master Sean, I should like to express my most humble apologies. I am an expert in my field. You are an expert on sorcery and sorcerers. Let it be so. The agreement has not been abrogated — nor, I trust, shall it ever be.”

He paused for a moment, then, after a deep breath, said, in a more normal tone of voice, “Of course, Master Sean. You may choose any kind of consultation you wish.”

During the moment of tension between the two friends, Lord Bontriomphe had quietly turned away, walked over to the corpse, and looked down at it without actually seeing it.

“Well, my lord—” There was just the slightest touch of embarrassment in Master Sean’s voice. He cleared his throat and began again. “Well, my lord, it wasn’t exactly consultation I was thinking of. What I really need is a good assistant. With your permission, I should like to ask Lord John Quetzal to help me. He’s only a journeyman, but he wants to become a forensic sorcerer and the experience will be good for him.”

“Of course, Master Sean, an excellent choice I should say. Now let me see—” He looked across at the body again. “I shan’t disturb the evidence any more than is necessary. Those ceremonial knives are all constructed to the same pattern, are they not?”

“Yes, my lord. Every sorcerer must make his own, with his own hands, but they are built to rigid specifications. That’s one of the things an apprentice has to learn right off, to build his own tools. You can’t use another man’s tools in this business, nor tools made by an ordinary craftsman. It’s the making of them that attunes them to the individual who uses them. They must be generally similar and individually different.”

“So I understand. Would you permit me to examine your own, so that I need not disturb Sir James’?”

“Of course.” He got the knife from his carpetbag and handed it to his lordship. “Mind you don’t cut yourself; that blade is razor sharp.”

Lord Darcy eased the onyx-handled knife from its black couirbouilli sheath. The gleaming blade was a perfect isosceles triangle, five inches from handguard to point and two inches wide at the handguard. Lord Darcy turned it and looked at the base of the pommel. “This is your monogram and symbol. I presume Sir James’ knife is identified in the same way?”

“Yes, my lord.”

“Would you mind looking at that knife and telling me whether you can positively identify it as his?”

“Oh, that’s the first thing I looked at. Many’s the time I’ve seen it, and it’s his knife, all right.”

“Excellent. That accounts for its being here.” He slid the deadly-looking blade back into its sheath and handed it back to the little sorcerer.

“That blade is pure silver, Master Sean?” Lord Bontriomphe asked.

“Pure silver, my lord.”

“Tell me: how do you keep a razor edge on anything that soft?”

Master Sean smiled broadly. “Well, I’ll admit it’s a hard job getting the edge on it in the first place. It has to be finished with jeweler’s rouge and very soft kidskin. But it’s only used as a symbolical knife, d’ye see. We never actually cut anything material with it, so it never needs to be sharpened again if a man’s careful.”

“But if you never cut anything with it,” said Lord Bontriomphe, “then why sharpen it at all? Wouldn’t it work as well if its edges were as dull as, say, a letter opener?”