Tuesday, October 9, 1866.

Serafina's wardrobe wasn't extensive, never expensive, wouldn't do, not for her class. The dress she chose to wear this morning, made of watered silk trimmed in velvet, was designed and crafted by Giulia, her middle daughter, in a style dated by a year or two. For daytime, she wore a single petticoat, not too full in front, with an undergarment of unbleached silk ruffled at the collar. She fastened the ivory brooch her mother gave her, rouged her lips, and called for Assunta to help with her hair.

"Not too busy, something simple," she told the domestic.

After Assunta left, she tied an embroidered net over her hair, just like Queen Maria Sofie would have worn. "Ready," she called out to the air in the room.

There was a rattling at the window panes. The candles flickered. Serafina felt the rush of air. A new smell, sharp, like shaved citrus and lavender, flooded the room.

A cloud appeared, faded, and, in its place, a specter, vaporous at first, almost invisible, a frescoed glaze upon the cushions of Giorgio's overstuffed chair. It grew more distinct, taking on the shape of a woman. Serafina saw her mother, Maddalena, crimson cheeked, skin moist, clothed in a gown of viridian deep. She'd forgotten how much like her own hair her mother's was, at least before hers started to fade. Her mother was younger than Serafina herself.

Maddalena's head turned in Serafina's direction, but gazed through her, at something beyond. Wrinkling her nose, she turned her attention to an object in her lap, a midwife's satchel. Her hands fiddled with the clasp. Her lips moved. She shook her head.

"Can't you say hello to your own daughter?" Serafina asked.

Hunching her shoulders, Maddalena plunged one arm into the bag. She rattled objects inside, as if stirring old bones.

"Carmela's gone and you do nothing. All alone, she is, knowing not of my death, nor of her father's. You must find her."

"But how?"

Maddalena stopped, lifted her head, wary and still, like a cat about to pounce. At the sound of footsteps, she vanished.

The doorknob turned.

"Are you coming? I'll be late for my lesson." Maria said. Her arms were full of schoolbooks and musical scores.

The Duomo's bell chimed the hour. Seven o'clock and Serafina's head ached.

Numbers.

Serafina and Maria traipsed across the piazza and opened the door to Lorenzo Coco's music store where Maria had a lesson each day before school.

She smelled sawdust, resin, and glue. Instruments hung from the rafters. Minerva's cello stood in the corner. The maestro was playing one of several harpsichords that sat the floor.

"How lovely. Scarlatti?"

"Mozart." He continued to play as they talked.

"Isn't it lovely, my precious?"

Maria hunched her shoulders.

"If only our little genius here would play pieces with more melody. I tell her she can't go wrong with Scarlatti, but all she's interested in at the moment is Brahms. Brahms this, Brahms that, chords crash."

Lorenzo twisted his mouth and finished his sonata.

Maria clutched her books to her chest. Shy, Serafina's youngest girl.

Serafina kissed her daughter goodbye. "Straight to school after your lesson."

Minerva entered the room, tapping a white cane in front of her.

Serafina pecked the maestra's cheeks. "I'd like your advice if I could steal some of your time while Maria takes her practice with the maestro."

"My studio. Follow me."

Serafina could hear Maria's scales while she told Minerva about the investigation. "Dr. Loffredo is certain the women were killed by the same man."

Minerva nodded.

"And I'm convinced he's a wild creature who doesn't kill for pleasure or to sate his appetite," Serafina said, "but the dates he's chosen to kill are significant in a way I don't understand. He has killed one victim a month for three consecutive months, each murder occurring sometime between the sixth and seventh day."

Minerva shuddered. "Not my field, numbers. But my brother is professor of mathematics, interested in the occult. I have an hour before my next lesson. I'll introduce you. He lives on the edge of town."

Professore Gasparo Rafaello lived alone in a small house filled with books. Not a dish out of place, no dust on the floor. After greetings were exchanged, the reason for their visit explained, and refreshments declined, they sat down.

The professor was a thin man. He wore a white shirt, grey vest, and sat on a wooden chair while the women faced him on the edge of a horsehair sofa. Minerva braced herself with her cane. Serafina squirmed. She hoped he was not long-winded.

A slight lisp obscured his words. Serafina strained to hear him. She reached in her reticule for her notebook and pencil.

With curled fingers he combed his mustache, addressing the two women as if they were students in a large auditorium. "So," he said.

A pause. Overlong.

Minerva said, "What? So what, Gasparo. Please to continue."

"What I know of the numbers, six and seven, I tell you now. Or..."

Another pause.

"Or?" Minerva asked.

"If you prefer, you can read my book, Numbers and Ecstasy.

"Tell us please," both women said in unison.

"So. Six is a perfect number," he said, looking first at his sister, then at Serafina.

"Please to get on with it," Minerva said.

"A perfect number is a whole number greater than zero. When you sum all of its factors, except for the number itself, you get that number."

Serafina rubbed her forehead. "I take your word for it. Six is a perfect number."

Minerva explained. "The factors of six are one, two, and three. When you add them, they make six. So six is a perfect number."

"Six is followed by twenty-eight, then four-hundred ninety-six, followed by-"

"Somehow I don't think the killer is a mathematician," Serafina said.

"Not too many murderers are interested in the genius of Euclid," Gasparo said, biting his mustache.

Minerva nodded.

He continued. "Now we come to the number, seven. According to the Greeks, it contains perfection, being the sum of the sides of an isosceles triangle and a square. The Romans, on the other hand, thought the number contained everything since it is the sum of four, the four corners of the earth, and three, a symbol of the divine."

Serafina thanked the professor. She and Minerva were about to depart when he stopped them. "Caught in the web of numerology, perhaps, your killer. But sometimes the mad will act according to the heavens, a full moon, for instance."

Serafina shook her head. "Not a full moon last Saturday. I would have remembered."

Midway home Minerva said, "Trouble ahead. Can we take another way?"

Serafina heard only a faint blowing in the distance, like the whisper of air through fronds. "Children playing?" she asked.

"Not children. Something else."

Her best choice was to trust Minerva's hearing and Largo's sense of direction, so she turned the trap and headed into a maze of narrow streets. The mule plowed through one twisted lane after another.

"I hope you know where you're going."

Largo brayed, increased his speed.

In a few moments, she could see the piazza.

As they drew closer, Serafina peered over her shoulder down a cross street and saw what must have caused the commotion, a crowd gathered around a cart. She slowed. An accident? A dodgy cart vendor? Voices grew louder. Pushing and shoving his way out from under the throng, a disheveled creature emerged, chased by a knot of yelling men. He pulled a swaybacked mule and weather-beaten cart.

"Poor man. Living rough, I suspect," Serafina said.

Minerva said nothing.

Serafina flicked the reins, stopped in front of Lorenzo's studio. She thanked her friend, kissed her on both cheeks, and led her inside.

The Autopsy.

Who else but Dr. Loffredo would sit at his desk with his breakfast served on fine china by a maid dressed in black with a white apron, a table linen tucked into the collar to protect his boiled shirt.

Pulling at the napkin, he came around to kiss Serafina's hand. So gentle his touch and understanding of women, and with eyes that would melt Scylla. Tall, not a hint of paunch, his clothes from the best tailors in Palermo. No children, a shame: they would have jammed that empty villa of his with offspring. She remembered their university days together, heady times, when class differences didn't matter and bedroom walls echoed with daring talk of revolution. A pity she had loved her Giorgio so much.

He held the back of her chair. "Latte, my dear?"

"Don't worry about me. Eat your breakfast while you tell me the results of the autopsy."

He rang the bell. "Too early in the day to talk of murder."

She ignored his remark. "Rosa asked me to investigate the deaths of her women."

"But you're a midwife." His gaze was tender.

She raised her shoulders, palms out. "My best friend, Rosa. I can't sit by while her business is destroyed. Colonna does nothing."

"The police have their hands full."

The maid entered, balancing a silver coffee service. She swept up his plate and left. Loffredo poured espresso and steaming milk, passed a cup to Serafina.

She said, "You've heard the rumors."

"Don Tigro?" Loffredo sipped his caffe.

"Doesn't make sense. Not to me. You?"

He shook his head. "Not the don's kind of killing, unless, of course, Rosa's not telling us everything."

"She doesn't hold things back from me." She paused. "Well, almost nothing."

He reached over and touched her hand.

"Spent time combing through Bella's room. I uncovered some information, nothing that gave me answers, only more questions." Serafina's gaze swept his face. She savored her first sip of latte, breathing in the cocoa, the caffe, and the steam. "To tell you the truth, I'm intrigued. Horrified, yes, but also fascinated by the prospect of sleuthing." She looked into his eyes. "Of late, my practice has been slow. Most families do their own birthing when coins are scarce, so no more coins from grateful fathers."

"Is it hard for you with Giorgio gone?" he asked.

Her face colored. She couldn't tell Loffredo coins were difficult. Wouldn't do. "Oh, that. We're fine. No worries there."

Loffredo swiped his mouth with fresh linen. "Be careful, Fina."

"You know me."

"Too well. Yes, you're a wizard, but sometimes it takes more than magic to right the world's wrongs."

"But I have to try."