Langdon had never heard the word agathusia, but took his best guess based on its Greek roots—agathos and thusia. “Agathusia … would be a ‘good sacrifice’?”

“Almost. Its actual meaning is ‘a self-sacrifice for the common good.’ ” She paused. “Otherwise known as benevolent suicide.”

Langdon had indeed heard this term before—once in relation to a bankrupt father who killed himself so his family could collect his life insurance, and a second time to describe a remorseful serial killer who ended his life fearing he couldn’t control his impulse to kill.

The most chilling example Langdon recalled, however, was in the 1967 novel Logan’s Run, which depicted a future society in which everyone gladly agreed to commit suicide at age twenty-one—thus fully enjoying their youth while not letting their numbers or old age stress the planet’s limited resources. If Langdon recalled correctly, the movie version of Logan’s Run had increased the “termination age” from twenty-one to thirty, no doubt in an attempt to make the film more palatable to the box office’s crucial eighteen-to-twenty-five demographic.

“So, Zobrist’s essay …” Langdon said. “I’m not sure I understand the title. ‘Who Needs Agathusia?’ Was he saying it sarcastically? As in who needs benevolent suicide … we all do?”

“Actually no, the title is a pun.”

Langdon shook his head, not seeing it.

“Who needs suicide—as in the W-H-O—the World Health Organization. In his essay, Zobrist railed against the director of the WHO—Dr. Elizabeth Sinskey—who has been there forever and, according to Zobrist, is not taking population control seriously. His article was saying that the WHO would be better off if Director Sinskey killed herself.”

“Compassionate guy.”

“The perils of being a genius, I guess. Oftentimes, those special brains, the ones that are capable of focusing more intently than others, do so at the expense of emotional maturity.”

Langdon pictured the articles he had seen about the young Sienna, the child prodigy with the 208 IQ and off-the-chart intellectual function. Langdon wondered if, in talking about Zobrist, she was also, on some level, talking about herself; he also wondered how long she would choose to keep her secret.

Up ahead, Langdon spotted the landmark he had been looking for. After crossing the Via dei Leoni, Langdon led her to the intersection of an exceptionally narrow street—more of an alleyway. The sign overhead read VIA DANTE ALIGHIERI.

“It sounds like you know a lot about the human brain,” Langdon said. “Was that your area of concentration in medical school?”

“No, but when I was a kid, I read a lot. I became interested in brain science because I had some … medical issues.”

Langdon shot her a curious look, hoping she would continue.

“My brain …” Sienna said quietly. “It grew differently from most kids’, and it caused some … problems. I spent a lot of time trying to figure out what was wrong with me, and in the process I learned a lot about neuroscience.” She caught Langdon’s eye. “And yes, my baldness is related to my medical condition.”

Langdon averted his eyes, embarrassed he’d asked.

“Don’t worry about it,” she said. “I’ve learned to live with it.”

As they moved into the cold air of the shadowed alleyway, Langdon considered everything he had just learned about Zobrist and his alarming philosophical positions.

A recurring question nagged at him. “These soldiers,” Langdon began. “The ones trying to kill us. Who are they? It makes no sense. If Zobrist has put a potential plague out there, wouldn’t everyone be on the same side, working to stop its release?”

“Not necessarily. Zobrist may be a pariah in the medical community, but he probably has a legion of devout fans of his ideology—people who agree that a culling is a necessary evil to save the planet. For all we know, these soldiers are trying to ensure that Zobrist’s vision is realized.”

Zobrist’s own private army of disciples? Langdon considered the possibility. Admittedly, history was full of zealots and cults who killed themselves because of all kinds of crazy notions—a belief that their leader is the Messiah, a belief that a spaceship is waiting for them behind the moon, a belief that Judgment Day is imminent. The speculation about population control was at least grounded in science, and yet something about these soldiers still didn’t feel right to Langdon.

“I just can’t believe that a bunch of trained soldiers would knowingly agree to kill innocent masses … all the while fearing they might get sick and die themselves.”

Sienna shot him a puzzled look. “Robert, what do you think soldiers do when they go to war? They kill innocent people and risk their own death. Anything is possible when people believe in a cause.”

“A cause? Releasing a plague?”

Sienna glanced at him, her brown eyes probing. “Robert, the cause is not releasing a plague … it’s saving the world.” She paused. “One of the passages in Bertrand Zobrist’s essay that got a lot of people talking was a very pointed hypothetical question. I want you to answer it.”

“What’s the question?”

“Zobrist asked the following: If you could throw a switch and randomly kill half the population on earth, would you do it?”

“Of course not.”

“Okay. But what if you were told that if you didn’t throw that switch right now, the human race would be extinct in the next hundred years?” She paused. “Would you throw it then? Even if it meant you might murder friends, family, and possibly even yourself?”

“Sienna, I can’t possibly—”

“It’s a hypothetical question,” she said. “Would you kill half the population today in order to save our species from extinction?”

Langdon felt deeply disturbed by the macabre subject they were discussing, and so he was grateful to see a familiar red banner hanging on the side of a stone building just ahead.

“Look,” he announced, pointing. “We’re here.”

Sienna shook her head. “Like I said. Denial.”

CHAPTER 51

The Casa di Dante is located on the Via Santa Margherita and is easily identified by the large banner suspended from the stone facade partway up the alleyway: MUSEO CASA DI DANTE.

Sienna eyed the banner with uncertainty. “We’re going to Dante’s house?”

“Not exactly,” Langdon said. “Dante lived around the corner. This is more of a Dante … museum.” Langdon had ventured inside the place once, curious about the art collection, which turned out to be no more than reproductions of famous Dante-related works from around the world, and yet it was interesting to see them all gathered together under one roof.

Sienna looked suddenly hopeful. “And you think they have an ancient copy of The Divine Comedy on display?”

Langdon chuckled. “No, but I know they have a gift shop that sells huge posters with the entire text of Dante’s Divine Comedy printed in microscopic type.”

She gave him a slightly appalled glance.

“I know. But it’s better than nothing. The only problem is that my eyes are going, so you’ll have to read the fine print.”

“È chiusa,” an old man called out, seeing them approach the door. “È il giorno di riposo.”

Closed for the Sabbath? Langdon felt suddenly disoriented again. He looked at Sienna. “Isn’t today … Monday?”

She nodded. “Florentines prefer a Monday Sabbath.”

Langdon groaned, suddenly recalling the city’s unusual weekly calendar. Because tourist dollars flowed most heavily on weekends, many Florentine merchants chose to move the Christian “day of rest” from Sunday to Monday to prevent the Sabbath from cutting too deeply into their bottom line.

Unfortunately, Langdon realized, this probably also ruled out his other option: the Paperback Exchange—one of Langdon’s favorite Florentine bookshops—which would definitely have had copies of The Divine Comedy on hand.

“Any other ideas?” Sienna said.

Langdon thought a long moment and finally nodded. “There’s a site just around the corner where Dante enthusiasts gather. I bet someone there has a copy we can borrow.”

“It’s probably closed, too,” Sienna warned. “Almost every place in town moves the Sabbath away from Sunday.”

“This place wouldn’t dream of doing such a thing,” Langdon replied with a smile. “It’s a church.”

Fifty yards behind them, lurking among the crowd, the man with the skin rash and gold earring leaned on a wall, savoring this chance to catch his breath. His breathing was not getting any better, and the rash on his face was nearly impossible to ignore, especially the sensitive skin just above his eyes. He took off his Plume Paris glasses and gently rubbed his sleeve across his eye sockets, trying not to break the skin. When he replaced his glasses, he could see his quarry moving on. Forcing himself to follow, he continued after them, breathing as gently as possible.

Several blocks behind Langdon and Sienna, inside the Hall of the Five Hundred, Agent Brüder stood over the broken body of the all-too-familiar spike-haired woman who was now lying sprawled out on the floor. He knelt down and retrieved her handgun, carefully removing the clip for safety before handing it off to one of his men.

The pregnant museum administrator, Marta Alvarez, stood off to one side. She had just relayed to Brüder a brief but startling account of what had transpired with Robert Langdon since the previous night … including a single piece of information that Brüder was still trying to process.

Langdon claims to have amnesia.

Brüder pulled out his phone and dialed. The line at the other end rang three times before his boss answered, sounding distant and unsteady.

“Yes, Agent Brüder? Go ahead.”

Brüder spoke slowly to ensure that his every word was understood. “We are still trying to locate Langdon and the girl, but there’s been another development.” Brüder paused. “And if it’s true … it changes everything.”

The provost paced his office, fighting the temptation to pour himself another Scotch, forcing himself to face this growing crisis head-on.

Never in his career had he betrayed a client or failed to keep an agreement, and he most certainly had no intention of starting now. At the same time he suspected that he might have gotten himself tangled up in a scenario whose purpose diverged from what he had originally imagined.

One year ago, the famous geneticist Bertrand Zobrist had come aboard The Mendacium and requested a safe haven in which to work. At that time the provost imagined that Zobrist was planning to develop a secret medical procedure whose patenting would increase Zobrist’s vast fortune. It would not be the first time the Consortium had been hired by paranoid scientists and engineers who preferred working in extreme isolation to prevent their valuable ideas from being stolen.

With that in mind, the provost accepted the client and was not surprised when he learned that the people at the World Health Organization had begun searching for him. Nor did he give it a second thought when the director of the WHO herself—Dr. Elizabeth Sinskey—seemed to make it her personal mission to locate their client.

The Consortium has always faced powerful adversaries.

As agreed, the Consortium carried out their agreement with Zobrist, no questions asked, thwarting Sinskey’s efforts to find him for the entire length of the scientist’s contract.

Almost the entire length.

Less than a week before the contract was to expire, Sinskey had somehow located Zobrist in Florence and moved in, harassing and chasing him until he committed suicide. For the first time in his career, the provost had failed to provide the protection he had agreed to, and it haunted him … along with the bizarre circumstances of Zobrist’s death.

He committed suicide … rather than being captured?

What the hell was Zobrist protecting?

In the aftermath of his death, Sinskey had confiscated an item from Zobrist’s safe-deposit box, and now the Consortium was locked in a head-to-head battle with Sinskey in Florence—a high-stakes treasure hunt to find …

To find what?

The provost felt himself glance instinctively toward the bookshelf and the heavy tome given to him two weeks ago by the wild-eyed Zobrist.

The Divine Comedy.

The provost retrieved the book and carried it back to his desk, where he dropped it with a heavy thud. With unsteady fingers, he opened the cover to the first page and again read the inscription.

My dear friend, thank you for helping me find the path.

The world thanks you, too.

First off, the provost thought, you and I were never friends.

He read the inscription three more times. Then he turned his eyes to the bright red circle his client had scrawled on his calendar, highlighting tomorrow’s date.

The world thanks you?

He turned and gazed out at the horizon a long moment.

In the silence, he thought about the video and heard the voice of facilitator Knowlton from his earlier phone call. I thought you might want to preview it before upload … the content is quite disturbing.

The call still puzzled the provost. Knowlton was one of his best facilitators, and making such a request was entirely out of character. He knew better than to suggest an override of the compartmentalization protocol.

After replacing The Divine Comedy on the shelf, the provost walked to the Scotch bottle and poured himself half a glass.

He had a very difficult decision to make.

CHAPTER 52

Known as the Church of Dante, the sanctuary of Chiesa di Santa Margherita dei Cerchi is more of a chapel than a church. The tiny, one-room house of worship is a popular destination for devotees of Dante who revere it as the sacred ground on which transpired two pivotal moments in the great poet’s life.