I entered the spiral steps first, but I noticed that he looked about the library before he followed, as though he wanted to be sure we were alone.

His breathing was heavy and deep, as he came behind me. I held my skirts to clear each step. We climbed for some minutes. I felt perspiration on my lip.

We reached a narrow gallery high in the cupola itself, close enough to touch the ceiling fresco. The paintings were distorted by the foreshortening that would make them seem natural when viewed from the floor of the library. Famous men of science peered at maps of new lands, directing their telescopes at the farthest horizon. The shading of their robes was made with gold crosshatching. They leaned against columns painted like soapy marble.

I glanced a hundred feet down. Fear stabbed in my stomach. I put my hand to my eyes and swayed against the bal.u.s.trade.

The baron took my wrist. "No, you must look, or you'll fall," he said.

I stumbled and found I was close to him.

"I apologize," I whispered. "I feel such tension."

"Because of the height?"

"Not only that. These things I've learned about Wolfgang's death. If he was involved in a mission to Prussia-"

"A mission?" He narrowed his eyes.

I leaned over the bal.u.s.trade again and lurid colors overcame my sight. I shut my eyes. "It might concern ruthless men. I don't know if I can safely investigate further. But I must, I owe it to Wolfgang."

I barely knew it, but he had taken my other hand, too, and drawn me to face him.

"Madame," he said.

I opened my eyes. The gold b.u.t.tons on his simple waistcoat angled to the light with each of his breaths, glinting.

"The emotions your singing evoked in me-" he said. "You understand? I-"

It had been love that almost lifted me into the air when I finished the aria. I couldn't pretend it was otherwise.

Still I tugged my hands from his grasp and hurried to the staircase. With my foot on the first step, I turned. He smiled distantly, as though recalling some long-ago happiness.

I descended the stairs, breathing harder than I had on the way up. I thought of my children on the sh.o.r.e of the Abersee. I wished that these steps, which seemed to go down forever, would open onto the village square on the day before Wolfgang died, and I might again be Frau Berchtold and not the woman who had survived an a.s.sault in the street and who was filled with fear and who loved a baron in the Imperial Palace.

Under the cupola, I turned a circle, looking for Swieten in the gallery high above me. I wanted to see him there, to feel his smile reach me.

Without a sound, he was before me. I lifted my foot to approach him. I would've thrown myself into his arms, had he not spoken, had he only reached for me.

"Tonight I will take you to hear The Magic Flute."

His voice was formal, as though on this floor he was the imperial librarian, rather than the man who had stammered about his feelings at the top of the stairs. But his eyes were gentle, and so only for a moment was I disconcerted.

"Yes," I said.

"First I want you to come with me. There's someone you ought to meet."

Chapter 23.

The baron's carriage turned into the entry of a well-appointed house on Backer Street. In a fresco above the gate, an unsuspecting cow rested beside a vicious wolf, a propaganda remnant of the wars between us Catholics and the Protestant heretics. As the carriage pa.s.sed under the entrance, I seemed to hear the painted predator snarl.

Swieten stepped down to the courtyard and held out his hand for me. When I took it, I shed the fear that had come over me with the wolf. On the wall behind him, two carved angels placed a gilded crown on a stone Madonna. Her blank face was accusing as I stood beside a man who had all but declared his love for me.

The baron led me up the steps to the seigneurial apartment. An external gallery ran from the stairs to the door, decorated with curling black wrought iron. He tugged on the bellpull. A peephole in the door slid back, and a pale, rheumy eye frowned through.

Swieten jerked his chin in command. The bolt went back and an old manservant ushered us into a dingy kitchen. I coughed at the foul odor in the room.

The manservant shuffled toward the front of the apartment. As we followed, the sting of sulfur grew stronger in the air.

We came to a darkened room which, I a.s.sumed, would have overlooked the street had the shutters been open. My eyes were adjusting to the blackness, when there was a burst of green light.

I cried out, and the baron's hand was on my arm once again. He removed it almost as quickly as the light faded. His touch shivered through me just as the brief flash had found every corner of the room.

The manservant opened a window to push the shutters back. The sulfurous scent cleared, replaced by the reek of animal feces and damp fodder. The salon was crowded with gla.s.s bottles and bubbling liquids.

A short man stepped into the shaft of light from the window. He wore an old-fashioned shoulder-length wig, its white curls framing a plump face that appeared younger than the headpiece. His stubby hands rubbed at a pair of spectacles with a cloth. His eyes bulged from their sockets, as though he were in the last moments of strangulation. He set the gla.s.ses on his nose, and his eyes disappeared into the thick lenses.

"Ah, my dear Baron van Swieten," the man said. "I apologize for any shock I may have caused."

"What was that eruption?" Swieten said.

"I'm trying to find a cure for toothache."

"With explosives?" Swieten leaned over the dishes and bottles on the table.

"With light."

The manservant shoved open the final shutter. Under the table, a dozen rabbits lounged in a cage on a layer of dirty straw.

"Everything is light and nothing more. Your tooth, too," the short man said, pushing his spectacles higher on his nose. " 'Let there be light.' Our Holy Bible tells us there was no existence before light, except for the spirit of G.o.d. This wall, this bench, you yourself-all just condensed light."

"Hence this experiment?"

"Ah, well, but that flash just now was an extraordinary effect I hadn't antic.i.p.ated. It didn't happen last time, not to that extent. Odd, most odd." The man reached under his wig and scratched at his neck.

Swieten inclined his head toward me. The little man rushed to kiss my hand.

"Dr. Matthias Sallaba, at your service, madame," he said. His cheeks were a lurid pink. Dry skin peeled in flakes the size of a thumbnail around his mouth. His face looked like the wall of a poor man's bas.e.m.e.nt, its plaster peeling away to reveal the brick beneath, mottled by neglect. He saw that I noticed these imperfections and he rubbed his neck again. "I've a little mercury poisoning, madame. Don't worry. It's not catching. The result of some experiments here in my laboratory."

"You must halt your experiments, then," I said.

He laughed and glanced at Swieten, who returned the smile.

"Then I'd never cure the toothache." Sallaba opened his mouth wide and pointed to his teeth. They were blotched with silvery gray lumps. "Dental amalgams, madame. I preserve my own teeth in my head and, therefore, may eat the sweetest foods with impunity."

Swieten dropped his hand onto the doctor's narrow shoulder. "In a few years, my dear Sallaba, you'll succ.u.mb to the poison. But we'll bury you with all your own teeth."

The doctor laughed hard, then shivered as though a spasm had gripped him. He clapped his hands. "You've come for your brother's death mask, madame?"

I stared at him. He took my silence for surprise that he had recognized me.

"I didn't get to know Maestro Mozart until his final days, when his face had puffed up a bit and he wasn't at his best," the doctor said, "but it's clear enough who you are."

He beckoned me to the corner of the room.

Beside a dangling skeleton, a gray plaster cast of Wolfgang's face rested on the sideboard. It showed more weight beneath his chin than I remembered, but I noticed the depression between his brows that I shared. The long nose, a little too wide at the end, was like mine, too. He was quiet now, his eyes shut and at peace, but the cast couldn't mask the suffering he had endured at the end. Suddenly I seemed to see the eyes open and the jaw spring wide to cry out in pain.

I clutched at my chest.

The doctor bent close to the death mask. Swieten laid his hand on my elbow in rea.s.surance.

"I'm quite sure I could've helped you, my poor fellow." Sallaba stroked the mask with a gentle, discolored finger. "They didn't call me in until the end. By then, it was too late for you."

"You could've helped me?" I said.

"What?" the doctor replied.

"Him, I mean. You could've helped him."

"It wouldn't have been easy, but his regular doctor, Closset, wasn't up to the job. He's more or less a medieval physician, like most doctors in Vienna. No idea about new treatments, no real science. All he knew to do was bleeding and cupping. Opened the poor fellow's veins, weakening him critically, just when he needed all his strength. Tortured him by placing the rims of hot cups on his flesh-drawing forth the bad vapors, he would've claimed."

The death mask called out its pain to me again.

"Dr. Closset attested that my brother expired of 'acute heated miliary fever,' " I said.

Sallaba grinned. "He also told me Herr Mozart had an excess of black bile building up. Our bodies, according to the ancient doctrine of Hippocrates, are balanced between blood, phlegm, and yellow and black bile. Too much of any one of these and we fall sick. Closset decided Maestro Mozart's black bile was building up in a deposit on his brain. That's why he bled him and gave him powders that would cause him to throw up-so that the black bile would stop moving to his brain."

"He made Wolfgang vomit?" I stammered.

"A big jet of it."

I whimpered. Swieten clicked his tongue and glared at Sallaba.

The doctor scuffed his shoe against the floor, embarra.s.sed. "He died right afterward. You might say Dr. Closset killed him. But there was probably nothing Closset could do. Because of his limited experience with poisons."

The doctor dribbled a few drops from a stone jar into a pan of liquid that had just come to the boil. The sulfurous smell returned.

"So Wolfgang was- He died by poison?" I said.

"Oh yes, most certainly," he said. "It's my specialty, you see. I've made a study of poisons, in my capacity as chair of forensic medicine at the university."

"How was he poisoned?"

"Well, not by mercury. Even Closset could've spotted that. Foul breath, cloudy urine, sweats. The same symptoms you find in the average syphilitic who's had too many doses of quicksilver in his member to counter the pox."

"Doctor, there's a lady present," Swieten said.

Sallaba looked up from the boiling pan, as though he had forgotten I was there. "Quite, quite," he said. "Poor Mozart was hallucinating at the end. He thought he was at a performance of The Magic Flute. He said, 'Quiet, the Queen of the Night is taking the high F. Listen, she's singing her second aria. How powerfully she hits the B-flat and holds it.' All the time staring off beyond the bed as though he were in a theater rather than a death room. Poor fellow."

"Doctor, how was he poisoned?"

"Acqua toffana. a.r.s.enic, lead, and belladonna," Sallaba said. "Tasteless, colorless. Deadly."

"How can you be sure?" I asked.

"Well, there was no autopsy, but the observable pathology points to poisoning."

"And the miliary fever?"

"My manservant has had one of those for some days now. He seems to be all right." The doctor called down the hallway. "Ignaz, have you been hallucinating? Burning pain in your mouth or throat?"

The rumbling voice of the servant came from the kitchen. "No, sir."

"Abdominal pain? Muscle spasms?" The doctor turned to me. "I can vouch that he has had no spasms. The old fellow barely moves a muscle. However, if you look at his skin, you'll see the rash like millet seeds that Dr. Closset entered in the Black List for your brother."

"The Black List?"

"The death register." Swieten coughed. "Doctor, something in here irritates my breathing."

Sallaba sniffed at the boiling liquid in his pan. "Really, that's interesting."

"What is it?"

"Just something I'm investigating. It bothers your lungs, does it?"

"Yes. Very much."

"Good, good. You know it's quite poisonous over a long period. But I'm intrigued that it had such an immediate effect on you-"

I rushed out of the room, past the doctor's disheveled bed, toward the kitchen and the door.

"Wait," the doctor called. "Don't you want the death mask?"

I leaned over the gallery outside and clutched at my stomach. An eddy of cold wind spiraled down through the courtyard, but the diabolical scent of Sallaba's poisons clung to my cloak. Swieten's coachman slouched against the flanks of his lead horse with a pipe in his mouth.

The baron came onto the gallery. "Madame, I apologize for the distress," he said. "I merely wanted to-"

"I'd like to pray for Wolfgang." I felt as though the gas circulating in the doctor's laboratory had filled me with the vapors of h.e.l.l itself. What scent enveloped the soul of my poor dead brother? "Take me to the cathedral."