I could summon Putrid. That was why the old rascal had not wanted me to lay out a tarot spread. My tarot was painted long ago by an artist of superlative skill and subtlety; since then the fears and yearnings of many owners have infused it with deep empathy. If I tried to consult it when I had a fiend in my immediate future, I might ruin it beyond repair.

The Maestro was a murder suspect and had to clear his name. He dare not risk asking a demon for help, but he would let me take that risk, because I needed help less than he did. Another reason was that I was less important and so, in a non-facetious way, relatively innocent. Summoning a minor fiend can stir up a major one instead. You never see senior condottieri fighting in the front ranks; they send the cannon fodder forward and shout encouragement from the rear, but any demon that managed to enslave the great Nostradamus would be capable of performing enormous mischief through him. All the legions of hell would rally to try it. I was mere cannon fodder.

I locked the door, then sat down at my desk and readied pen and paper. A summoning needs careful planning. Even my trivial fiend Putrid can be a terrifying apparition, and to panic and forget what comes next or change plans halfway through could be disastrous. It would do no good to demand, “Tell me who killed Procurator Orseolo,” or even “Procurator Bertucci Orseolo” because there might have been several men of that name in the history of the Republic. And the fiend could just reply “his doctor,” which might be true in a narrow sense. After much thought I wrote down two questions, plus the command of dismissal, which demonologists have been known to forget in emergencies, although none ever more than once. Purists conduct their summonings in Latin. The Maestro says that the fiends themselves don’t care what language you use and it is better to be right than classy.

I moved a chair over to the big mirror in the wall of books. Mirrors themselves are no more magical than crystal balls, but both can be used for occult purposes, like the piece of chalk I used to draw a pentacle around myself and the chair. I sat down, tried some deep breaths, and then uttered my first call, summoning Putrid (not his real name) to be manifest in the mirror before me.

The room cooled and dimmed. It always shocks me when mere words can do that. Even the flames in the fireplace seemed to shrink, and I wished I had brought a lamp inside the pentacle with me.

I summoned a second time. Now the mirror showed very little more than my own white face with darkness behind it, and the air was filled with a nauseating stench. Think of every bad smell you have ever experienced-bad fish, cesspools, warm pig dung-add them all together and multiply by thirteen. Gagging, anxious to get the seance over with, I spoke the words a third time.

My scared face in the mirror blurred and melted into a reddish globe, which shrank back and resolved as the iris of an eye. The surrounding space cleared into scaly, scabrous flesh of an indeterminate green-purple color, like a very ripe bruise. The monster moved farther back yet, until a second eye came into view. Whatever shade or shape they choose for the rest of themselves, fiends always seem to prefer red eyes. Putrid had begun his apparition the size of a house, and even now I could see only part of his face peering in, huge as the mirror was. The less I saw the better.

“You!” he said. He slobbered and his breath stank even worse than the rest of him. “I will eat you.”

I peered at my script in the feeble firelight.

“You have a nice smell of fresh sin on you, sier Alfeo Zeno,” the fiend said chattily. “You should have been shriven before you called me. And your harlot also I will eat.”

Another rule is that you never listen to fiends.

“Putrid, I command you by your true name that if there was no murderer present on San Valentine’s Eve last in the room in this city where Ottone Imer the attorney displayed books to certain potential buyers, that you instantly quit this realm and return to the place from whence you came.”

The fiend coughed, spraying the inside of the mirror with spit and almost choking me with putrescent fumes. My skin crawled.

“That’s clever,” he growled. “Thought that up all by yourself, did you, Alfeo?” He was still there, which disposed of any last hope that the procurator’s death had been an accident.

“Look, Alfeo,” the fiend said. “Violetta with her customers. Let me show you what she does, Alfeo. Look!”

I did not look. “Putrid, I command you by your true name that until and only until I clap my hands three times you show me in this mirror before me the murder committed by the murderer who was present on San Valentine’s Eve last in the room in this city where Ottone Imer the attorney displayed books to certain potential buyers, and I further command you by your true name that when and only when I clap my hands three times that you instantly quit this realm and return to the place from whence you came.”

“Damn you,” the fiend muttered, but the hideous images faded from the mirror.

I was staring down into a tent. It was dim, lit by two small lamps suspended from the ridge pole, but luxuriously carpeted and furnished with elaborate chests, a divan, a silver ewer and basin. Steel mail and a sword hung on a stand by the entrance. Seemingly right below me, a man sat cross-legged on a cushion under the lamps, reading. I could see that the writing was Arabic, and needed no demon to advise me that I was spying on one of the sultan’s generals. His face was hidden from me by a turban shaped like a giant pumpkin, much bigger than his head, but he wore a sleeveless tunic and a complicated, multicolored skirt that barely reached his knees. He could not be the sultan himself-unlike his warlike ancestors, he stays home in safety in Constantinople, and he would command far grander quarters if he did venture into the field-but someone of importance. What was Putrid playing at? What loophole had I left in my instructions?

The man looked up, frowning and tilting his head as if listening to something. He was dusky and weathered; he had silver streaks in his beard, but his face was lean, vulpine, and still dangerous.

The flap lifted to admit a second man. He was young, short but heavyset, swarthy and bearded, and he wore very similar garb. He salaamed to the general. There must be millions like him in the Ottoman Empire, from Hungary to the Persian Gulf, from Libya to the Caucasus-fierce Muslims all, fanatically loyal to their sultan-but very few of those would have a fiend sitting on one shoulder as this one did. In shape the horror resembled a tailless rat with red eyes and a grin that showed sharp teeth, but its texture was slug-like, bluish and slimy.

The general had risen, but he clearly did not register the fiend, because he listened calmly to whatever the visitor said. I could not hear a word and would not have understood it if I had. The general salaamed in response to whatever message or instructions he had just received. He went over to the portable table with the ewer and basin and there proceeded to wash his hands. The visitor watched, smiling contentedly, while the fiend hugged itself in glee and chomped its teeth.

I still had no idea what was going on; I just knew that I could not approve of anything that a demon enjoyed so much. No doubt there are possessed walking the streets of Christendom, too, even here in the Republic. I was identifying this one and his rider only because I was seeing them through Putrid’s eyes.

Hands washed, the general returned to the center of the tent, knelt down with his back to his guest, and began to pray in the Muslims’ fashion, bending to touch the rug with his forehead, leaning back to raise his arms. To my astonishment, the fiend disappeared. The visitor did not seem to notice its absence any more than he had shown awareness of its presence earlier. What surprised me was that the Muslim’s prayers had dispelled it at least as effectively as a Christian’s would. Was the name of Allah as effective as the name of Christ? That was certainly not what the Church taught. If the unbelievers worshipped the Antichrist, how could their prayers banish demons? I would be burned as a heretic if I ever suggested such a thing.