“It was cast by Grand Master Sir Lyon himself,” said Lord Darcy.

“Then I’ll go fetch him to take it off,” said Master Sean. “I wouldn’t waste time trying to take it off meself.”

“Pardon me, Master Sorcerer,” said Armsman Jeffers deferentially, “are you Master Sean O Lochlainn?”

“That I am.”

The Armsman took an envelope from an inside jacket pocket. “The Grand Master,” he said, “told me to be sure and give this to you when you came, Master Sean.”

Master Sean placed his symbol-decorated carpetbag on the floor, took the envelope, opened it, extracted a single sheet of paper, and read it carefully.

“Ah!” he said, his round Irish face beaming. “I see! Ingenious! I shall most certainly have to remember that one!” He looked at Lord Darcy with the smile still wreathing his face. “Sir Lyon has given me the key. He expected me to be here this morning. Now, if you’ll excuse me for a few minutes—”

The tubby little Irish sorcerer knelt down and opened his carpetbag. He fished around inside and took out a gold-and-ebony wand, a small brazen bowl, an iron tripod with six-inch legs, two silver phials, and an oddly constructed flint-and-steel fire-striker.

The others stepped back respectfully. One does not disturb a magician at work.

Master Sean placed the tripod on the floor just in front of the open door and set the small brazen bowl on top of it. Then he put in a few lumps of charcoal from his carpetbag. Within two minutes, he had the coals glowing redly. Then he added a large pinch of powder from each of the two silver phials, and a dense column of aromatic blue-gray smoke arose from the small brazier. Master Sean traced a series of symbols in the air with his wand while he murmured something the others could not hear. Then he carefully folded, in an intricate and complex manner, the letter from Sir Lyon Grey. When it was properly folded, he dropped it on the coals. As it burst into flame, he traced more symbols and murmured further words.

“There,” he said. “You can go in now, my lords.”

The two investigators walked across the threshold. Their aversion to doing so had completely vanished. Master Sean took a small bronze lid from his carpetbag and fitted it tightly over the mouth of the little brazier.

“Just leave it there, lads,” he said to the two Armsmen. “It will cool off in a few minutes. Mind you don’t knock it over, now.” Then he joined Lord Darcy and Lord Bontriomphe inside the murder room.

Lord Darcy closed the door and looked at it. From the inside, the damage done by Lord Bontriomphe’s ax work was plainly visible. Otherwise, there was nothing unusual about the door. A rapid but thorough inspection of the doors and windows convinced Lord Darcy that Lord Bontriomphe had been absolutely right when he said the room was sealed. There were no secret panels, no trapdoors. The windows were firmly bolted, and there was no way they could have been bolted from the outside by other than magical means.

With difficulty, Lord Darcy slid back the bolt on one of the windows and opened it. It creaked gently as it swung outward.

Lord Darcy looked out the window. There was a thirty-foot drop of smooth stone beneath him. The window opened onto a small courtyard, where several chair-surrounded tables formed a part of the dining facilities of the Royal Steward Hotel.

Some of the tables were occupied. Five sorcerers, three priests, and a bishop had all heard the window open and were looking up at him.

Lord Darcy craned his neck around and looked up. Ten feet above were the windows of the next floor. Lord Darcy pulled his head back in and closed the window.

“No one went out that way,” he said firmly. “For an ordinary man to have done so would have required a rope. He would have had either to slide down thirty feet or to climb up ten feet hand over hand.”

“An ordinary man,” said Lord Bontriomphe, emphasizing the word. “But levitation is not too difficult a trick for a Master Sorcerer.”

“What say you, Master Sean?” Lord Darcy asked the tubby little sorcerer.

“It could have been done that way,” Master Sean admitted.

“Furthermore,” said Lord Bontriomphe, “those bolts could have been thrown from the outside by magic.”

“Indeed they could,” Master Sean agreed.

Lord Bontriomphe looked expectantly at Lord Darcy.

“Very well,” said Lord Darcy with a smile, “let us proceed to try that theory by what the geometers call, I believe, the reductio ad absurdum. Imagine the scene. What happens?”

He gestured toward the body on the floor. “Sir James is stabbed. Our sorcerer-murderer — if you’ll pardon the double entendre — goes to the window. He opens it. Then he steps up to the sill and steps out into empty air, levitating himself as he does so. Then he closes the window and proceeds to cast a spell which slides the bolts into their sockets. When that is done, he floats off somewhere — up or down, it matters not which.” He looked at Master Sean. “How long would that take?”

“Five or six minutes at the least. If he could do it at all. Levitation causes a tremendous psychic drain; the spell can only be held for a matter of minutes. In addition, you’re asking him to cast a second spell while he’s holding the first. A spell of the type that was cast on this room is what we call a static spell, my lord. It imposes a condition, you see. But levitating and the moving of bolts are kinetic spells; you have to keep them moving. To use two kinetic spells at the same time requires tremendous concentration, power, and precision. I would hesitate, myself, to try casting a window-locking spell with a thirty-foot drop beneath me. Certainly not if I were in a hurry or distracted.”

“And even if it could be done, it would take five or six minutes,” Lord Darcy said. “Bontriomphe, would you mind opening the other window? We haven’t tested it yet.”

The London investigator drew back the bolt and pushed the window open. It groaned audibly.

“What do you see out there?” Lord Darcy asked.

“About nine pairs of eyes staring up at me,” Lord Bontriomphe said.

“Exactly. Both windows make a slight noise when they are opened. That noise is quite audible in the courtyard below. Yesterday morning, Sir James’ scream was clearly audible through that window, but even if it had not been — even if Sir James had not screamed at all when he was stabbed — the killer could not have gone out through that window without being seen, much less hovered there for five or six minutes.”

Lord Bontriomphe pulled the window closed again. “What if he were invisible?” he asked, looking at the little Irish sorcerer.

“The Tarnhelm Effect?” asked Master Sean. He chuckled. “My lord, regardless of what the layman may think, the Tarnhelm Effect is extremely difficult to use in practice. Besides, ‘invisibility’ is a layman’s term. Spells using the Tarnhelm Effect are very similar in structure to the aversion spell you met at the door to this room. If a sorcerer were to cast such a spell about himself, your eyes would avoid looking directly at him. You wouldn’t realize it yourself, but you would simply keep your eyes averted from him at all times. He could stand in the middle of a crowd and no one could later swear that he was there because no one would have seen him except out of the corner of the eye, if you follow me.

“Even if he were alone, you wouldn’t see him because you’d never look at him. You would subconsciously assume that whatever it was you were seeing out of the corner of your eye was a cabinet or a hatrack or an umbrella stand or a lamppost — whatever was most likely under the circumstances. Your mind would explain him away as something that ought to be there, as a part of the normal background and therefore unnoticeable.

“But he wouldn’t actually be invisible. You could see him, for instance, in a mirror or other reflecting surface simply because the spell wouldn’t keep your eyes away from the mirror.”