“I do not know what the others did, messer Alfeo. I laid mine down so I could assist my grandfather. He drained his glass and handed it to me in exchange for his cane, which I had been holding. And he pulled a face.”

“What sort of face?” Benedetto demanded.

Bianca lowered her eyes again. “A grimace. As if he had not liked the taste. He did not say anything. I did not ask him. Sier Alfeo, would it have made any difference if-”

I said, “None at all. There is no known antidote. You could have done nothing. Had you realized he had been poisoned, then a finger down the throat to induce vomiting might have helped at that early stage, but even that could be dangerous to an old man. He might well have choked. You had no reason to suspect foul play. He did not, obviously. Who has not unexpectedly found bitter lees in the bottom of a wineglass? And perhaps that was all it was.”

I doubt she believed me, but she whispered, “Thank you.”

“The wine was poisoned?” her brother said furiously. “The waiters have been questioned?”

“Other people drank from the same bottle,” I said. “Did the procurator set his glass down while he was looking at the books, madonna?”

She nodded. “And when he moved to another, I sometimes picked it up and carried it for him, but usually he did that himself. I am certain I never picked up the wrong glass, and almost certain he never did, either. I was watching, because he was getting forgetful. That was why I was there, to help him.”

Bianca had been the best-positioned witness, yet even she had not seen the killer strike. Had there even been a killer? My hopes of exposing a murderer sank to the bottom of the Adriatic Sea.

“Do not distress yourself with such thoughts!” I said. “Very few people were drinking retsina. He would have known if he had accidentally taken some other person’s drink-would have known by the smell before his first sip. His death was not your fault and it was not an accident. Either his glass was deliberately poisoned or it was switched with one that had been.”

“No, messer! If anyone had tampered with his drink I would have seen.”

“Bianca!” snapped her brother. “Be careful what you say.”

“She is only trying to help,” I said. “Nobody suspects her.” I could not imagine that angelic face belonging to a sinner guilty of anything. “She would not have made that statement if she had poisoned the wine herself! Did your grandfather have anything else to eat or drink? Antipasto?”

She shook her head. “We joined the other guests in the salone, but he refused more wine. At the table he took ill before the antipasto was served.”

The mystery now looked more impossible than insoluble. The Maestro had been mistaken, the procurator had died of natural causes.

“You have been extremely helpful, madonna,” I said. “Did anything else happen in the book room that we should know?”

She smiled. “There was a fight! Well, an argument. Our host discovered the two foreigners and asked them their names. Then he told them to leave, politely at first. The man became offensive and said he had been invited. The illustrious Karagounis was brought into the argument. Maestro Nostradamus had to translate back and forth. At one point the foreign man took out a purse and shook it in Attorney Imer’s face.”

Before I could ask anything more, I heard steps and looked around at the trouble approaching, Great Minister Enrico Orseolo, who had tried to beat me down from ten ducats to three for work already delivered while he was standing under a Tintoretto painting as big as the Piazzetta.

Whenever noblemen over the age of twenty-five appear in public, they wear floor-length robes, a tippet over one shoulder, and a flat, round bonnet like a cake. Magistrates wear color, all others black. As a great minister, sier Enrico Orseolo would wear violet instead of black, but now mourning had put him back in black, a trailing gown like his son’s. Alessa had described him as cold on the outside, warm inside, but I thought of him as cold-blooded. My private name for him was Lizard, because his eyes were protuberant, heavy-lidded, creepily unblinking, while the rest of his face was gaunt and fleshless. He was said to be a politician’s politician, a conciliator, a maker of deals, and I knew he was the sort of man to value agreement for its own sake, not caring whether its terms are honorable-anything was negotiable. His offers to settle the Maestro’s bill had gone up one ducat at a time.

I got the full amount in the end, though.

Enrico Orseolo, the procurator’s son, last survivor of the family group I had inspected earlier, Alessa’s sometime patron, possible future member of the Council of Ten, came to a halt and looked us over with glassy indifference. He did not quite flicker a forked tongue at us, but I imagined it. Today he was not in a mood to compromise.

“Who are these people, Benedetto? What are they doing here?” His gaze fixed on me. “Don’t I know you?”

I bent to kiss his sleeve. “Alfeo Zeno, Your Excellency, apprentice to Doctor Nostradamus, the physician who-”

“The astrologer. Yes, I remember. He took advantage of an old man’s gullibility, and you were an insolent pest. What are you doing here? You, cover your face!” That last remark was directed at Bianca and the next to Benedetto. “You are supposed to be supervising the servants.”

Son and daughter hurriedly departed. His Excellency turned back to me.

I began at the beginning, with his father’s collapse. I did not get very far.

“ Who poisoned his wine?”

“That is what I am trying to-”

“Did my daughter see it happen?”

“Apparently not, Your-”

“Then I am confident it did not happen at all. If your charlatan master thinks he has evidence of foul play, he should take his suspicions to the Ten. I will not tolerate vicious gossip about my family or my late father and the next time you or he meddle in my affairs, boy, I will denounce him as a mountebank to the state inquisitors.”

Now he would turn his reptilian gaze on the nun. Violetta was veiled again, although I had not seen her move, but he might still recognize her as the celebrated courtesan. I had to distract him, which was easy enough. I can tolerate abuse directed at me, but I will not stand by and let people denigrate the Maestro.

“Mountebank, clarissimo? That horoscope you repeatedly described as a worthless piece of parchment would have saved your father’s life, had you or he paid better attention to it. My master warned him to beware the coming of the lover and he was murdered on the eve of the feast of San Valentino. I would have thought ten ducats was little enough to have paid for-”

Sier Enrico was quite smart enough to see the potential for ridicule if he tried to carry out his threat. His eyes bulged even farther. “Get out! Get out of here!” He wheeled around to Violetta. “Who are you and why are you here?”

“I am another charlatan.” She spoke with Medea’s voice. “Your manners may be forgiven on account of your bereavement, for which I offer my condolences and my prayers. Let us go, sier Alfeo.”

Enrico Orseolo snorted at hearing my title. He probably stood and watched us leave, but I did not turn around to look. I hate being seen off as much as any man does, but this did seem a propitious time to leave.

“Pretty girl,” Medea said as we descended the great staircase.

“I suppose so.”

“Suppose? I was frightened someone would step on your tongue, it was hanging out so far. And her father is absolutely charming. You are old playmates, are you, you two?”

“Something like that,” I admitted. “My master has a rule that a horoscope is confidential and must be delivered into the client’s own hand. I often have to talk my way up the chain, from skivvy to footman to majordomo to people with names. And then I have to collect the money, which can take several more visits. I got to know the Orseolo household quite well.”