Knowlton fast-forwarded from the beginning, looking for any clue he might have missed. He skipped past the submerged plaque … past the suspended bag of murky yellow-brown liquid … and found the moment that the beak-nosed shadow appeared—a deformed silhouette cast upon a dripping cavern wall … illuminated by a soft red glow.

Knowlton listened to the muffled voice, attempting to decipher the elaborate language. About halfway through the speech, the shadow on the wall suddenly loomed larger and the sound of the voice intensified.

Dante’s hell is not fiction … it is prophecy!

Wretched misery. Torturous woe. This is the landscape of tomorrow.

Mankind, if unchecked, functions like a plague, a cancer … our numbers intensifying with each successive generation until the earthly comforts that once nourished our virtue and brotherhood have dwindled to nothing … unveiling the monsters within us … fighting to the death to feed our young.

This is Dante’s nine-ringed hell.

This is what awaits.

As the future hurls herself toward us, fueled by the unyielding mathematics of Malthus, we teeter above the first ring of hell … preparing to plummet faster than we ever fathomed.

Knowlton paused the video. The mathematics of Malthus? A quick Internet search led him to information about a prominent nineteenth-century English mathematician and demographist named Thomas Robert Malthus, who had famously predicted an eventual global collapse due to overpopulation.

Malthus’s biography, much to Knowlton’s alarm, included a harrowing excerpt from his book An Essay on the Principle of Population:

The power of population is so superior to the power in the earth to produce subsistence for man, that premature death must in some shape or other visit the human race. The vices of mankind are active and able ministers of depopulation. They are the precursors in the great army of destruction; and often finish the dreadful work themselves. But should they fail in this war of extermination, sickly seasons, epidemics, pestilence, and plague, advance in terrific array, and sweep off their thousands and ten thousands. Should success be still incomplete, gigantic inevitable famine stalks in the rear, and with one mighty blow levels the population with the food of the world.

With his heart pounding, Knowlton glanced back at the paused image of the beak-nosed shadow.

Mankind, if unchecked, functions like a cancer.

Unchecked. Knowlton did not like the sound of that.

With a hesitant finger, he started the video again.

The muffled voice continued.

To do nothing is to welcome Dante’s hell … cramped and starving, weltering in Sin.

And so boldly I have taken action.

Some will recoil in horror, but all salvation comes at a price.

One day the world will grasp the beauty of my sacrifice.

For I am your Salvation.

I am the Shade.

I am the gateway to the Posthuman age.

CHAPTER 34

The Palazzo Vecchio resembles a giant chess piece. With its robust quadrangular facade and rusticated square-cut battlements, the massive rooklike building is aptly situated, guarding the southeast corner of the Piazza della Signoria.

The building’s unusual single spire, rising off center from within the square fortress, cuts a distinctive profile against the skyline and has become an inimitable symbol of Florence.

Built as a potent seat of Italian government, the building imposes on its arriving visitors an intimidating array of masculine statuary. Ammannati’s muscular Neptune stands naked atop four sea horses, a symbol of Florence’s dominance in the sea. A replica of Michelangelo’s David—arguably the world’s most admired male nude—stands in all his glory at the palazzo entrance. David is joined by Hercules and Cacus—two more colossal naked men—who, in concert with a host of Neptune’s satyrs, bring to more than a dozen the total number of exposed penises that greet visitors to the palazzo.

Normally, Langdon’s visits to the Palazzo Vecchio had begun here on the Piazza della Signoria, which, despite its overabundance of phalluses, had always been one of his favorite plazas in all of Europe. No trip to the piazza was complete without sipping an espresso at Caffè Rivoire, followed by a visit to the Medici lions in the Loggia dei Lanzi—the piazza’s open-air sculpture gallery.

Today, however, Langdon and his companion planned to enter the Palazzo Vecchio via the Vasari Corridor, much as Medici dukes might have done in their day—bypassing the famous Uffizi Gallery and following the corridor as it snaked above bridges, over roads, and through buildings, leading directly into the heart of the old palace. Thus far, they had heard no trace of footsteps behind them, but Langdon was still anxious to exit the corridor.

And now we’ve arrived, Langdon realized, eyeing the heavy wooden door before them. The entrance to the old palace.

The door, despite its substantial locking mechanism, was equipped with a horizontal push bar, which provided emergency-exit capability while preventing anyone on the other side from entering the Vasari Corridor without a key card.

Langdon placed his ear to the door and listened. Hearing nothing on the other side, he put his hands against the bar and pushed gently.

The lock clicked.

As the wooden portal creaked open a few inches, Langdon peered into the world beyond. A small alcove. Empty. Silent.

With a small sigh of relief, Langdon stepped through and motioned for Sienna to follow.

We’re in.

Standing in a quiet alcove somewhere inside the Palazzo Vecchio, Langdon waited a moment and tried to get his bearings. In front of them, a long hallway ran perpendicular to the alcove. To their left, in the distance, voices echoed up the corridor, calm and jovial. The Palazzo Vecchio, much like the United States Capitol Building, was both a tourist attraction and a governmental office. At this hour, the voices they heard were most likely those of civic employees bustling in and out of offices, getting ready for the day.

Langdon and Sienna inched toward the hallway and peered around the corner. Sure enough, at the end of the hallway was an atrium in which a dozen or so government employees stood around sipping morning espressi and chatting with colleagues before work.

“The Vasari mural,” Sienna whispered, “you said it’s in the Hall of the Five Hundred?”

Langdon nodded and pointed across the crowded atrium toward a portico that opened into a stone hallway. “Unfortunately, it’s through that atrium.”

“You’re sure?”

Langdon nodded. “We’ll never make it through without being seen.”

“They’re government workers. They’ll have no interest in us. Just walk like you belong here.”

Sienna reached up and gently smoothed out Langdon’s Brioni suit jacket and adjusted his collar. “You look very presentable, Robert.” She gave him a demure smile, adjusted her own sweater, and set out.

Langdon hurried after her, both of them striding purposefully toward the atrium. As they entered, Sienna began talking to him in rapid Italian—something about farm subsidies—gesticulating passionately as she spoke. They kept to the outer wall, maintaining their distance from the others. To Langdon’s amazement, not one single employee gave them a second glance.

When they were beyond the atrium, they quickly pressed onward toward the hallway. Langdon recalled the Shakespeare playbill. Mischievous Puck. “You’re quite an actress,” he whispered.

“I’ve had to be,” she said reflexively, her voice strangely distant.

Once again, Langdon sensed there was more heartache in this young woman’s past than he knew, and he felt a deepening sense of remorse for having entangled her in his dangerous predicament. He reminded himself that there was nothing to be done now, except to see it through.

Keep swimming through the tunnel … and pray for light.

As they neared their portico, Langdon was relieved to see that his memory had served him well. A small plaque with an arrow pointed around the corner into the hallway and announced: IL SALONE DEI CINQUECENTO. The Hall of the Five Hundred, Langdon thought, wondering what answers awaited within. The truth can be glimpsed only through the eyes of death. What could this mean?

“The room may still be locked,” Langdon warned as they neared the corner. Although the Hall of the Five Hundred was a popular tourist destination, the palazzo did not appear to be open yet to tourists this morning.

“Do you hear that?” Sienna asked, stopping short.

Langdon heard it. A loud humming noise was coming from just around the corner. Please tell me it’s not an indoor drone. Cautiously, Langdon peered around the corner of the portico. Thirty yards away stood the surprisingly simple wooden door that opened into the Hall of the Five Hundred. Regrettably, directly between them stood a portly custodian pushing an electric floor-buffing machine in weary circles.

Guardian of the gate.

Langdon’s attention shifted to three symbols on a plastic sign outside the door. Decipherable to even the least experienced of symbologists, these universal icons were: a video camera with an X through it; a drinking cup with an X through it; and a pair of boxy stick figures, one female, one male.

Langdon took charge, striding swiftly toward the custodian, breaking into a jog as he drew nearer. Sienna rushed behind him to keep up.

The custodian glanced up, looking startled. “Signori?!” He held out his arms for Langdon and Sienna to stop.

Langdon gave the man a pained smile—more of a wince—and motioned apologetically toward the symbols near the door. “Toilette,” he declared, his voice pinched. It was not a question.

The custodian hesitated a moment, looking ready to deny their request, and then finally, watching Langdon shift uncomfortably before him, he gave a sympathetic nod and waved them through.

When they reached the door, Langdon gave Sienna a quick wink. “Compassion is a universal language.”

CHAPTER 35

At one time, the Hall of the Five Hundred was the largest room in the world. It had been built in 1494 to provide a meeting hall for the entire Consiglio Maggiore—the republic’s Grand Council of precisely five hundred members—from which the hall drew its name. Some years later, at the behest of Cosimo I, the room was renovated and enlarged substantially. Cosimo I, the most powerful man in Italy, chose as the project’s overseer and architect the great Giorgio Vasari.

In an exceptional feat of engineering, Vasari had raised the original roof substantially and permitted natural light to flow in through high transoms on all four sides of the room, resulting in an elegant showroom for some of Florence’s finest architecture, sculpture, and painting.

For Langdon, it was always the floor of this room that first drew his eye, immediately announcing that this was no ordinary space. The crimson stone parquet was overlaid with a black grid, giving the twelve-thousand-square-foot expanse an air of solidity, depth, and balance.

Langdon raised his eyes slowly to the far side of the room, where six dynamic sculptures—The Labors of Hercules—lined the wall like a phalanx of soldiers. Langdon intentionally ignored the oft-maligned Hercules and Diomedes, whose naked bodies were locked in an awkward-looking wrestling match, which included a creative “penile grip” that always made Langdon cringe.

Far easier on the eyes was Michelangelo’s breathtaking Genius of Victory, which stood to the right, dominating the central niche in the south wall. At nearly nine feet tall, this sculpture had been intended for the tomb of the ultraconservative pope Julius II—Il Papa Terribile—a commission Langdon had always found ironic, considering the Vatican’s stance on homosexuality. The statue depicted Tommaso dei Cavalieri, the young man with whom Michelangelo had been in love for much of his life and to whom he composed over three hundred sonnets.

“I can’t believe I’ve never been here,” Sienna whispered beside him, her voice suddenly quiet and reverent. “This is … beautiful.”

Langdon nodded, recalling his first visit to this space—on the occasion of a spectacular concert of classical music featuring the world-renowned pianist Mariele Keymel. Although this grand hall was originally intended for private political meetings and audiences with the grand duke, nowadays it more commonly featured popular musicians, lecturers, and gala dinners—from art historian Maurizio Seracini to the Gucci Museum’s star-studded, black-and-white gala opening. Langdon sometimes wondered how Cosimo I would feel about sharing his austere private hall with CEOs and fashion models.

Langdon lifted his gaze now to the enormous murals adorning the walls. Their bizarre history included a failed experimental painting technique by Leonardo da Vinci, which resulted in a “melting masterpiece.” There had also been an artistic “showdown” spearheaded by Piero Soderini and Machiavelli, which pitted against each other two titans of the Renaissance—Michelangelo and Leonardo—commanding them to create murals on opposite walls of the same room.

Today, however, Langdon was more interested in one of the room’s other historical oddities.

Cerca trova.

“Which one is the Vasari?” Sienna asked, scanning the murals.

“Nearly all of them,” Langdon replied, knowing that as part of the room’s renovation, Vasari and his assistants had repainted almost everything in it, from the original wall murals to the thirty-nine coffered panels adorning its famed “hanging” ceiling.

“But that mural there,” Langdon said, pointing to the mural on their far right, “is the one we came to see—Vasari’s Battle of Marciano.”

The military confrontation was absolutely massive—fifty-five feet long and more than three stories tall. It was rendered in ruddy shades of brown and green—a violent panorama of soldiers, horses, spears, and banners all colliding on a pastoral hillside.

“Vasari, Vasari,” Sienna whispered. “And hidden in there somewhere is his secret message?”

Langdon nodded as he squinted toward the top of the huge mural, trying to locate the particular green battle flag on which Vasari had painted his mysterious message—CERCA TROVA. “It’s almost impossible to see from down here without binoculars,” Langdon said, pointing, “but in the top middle section, if you look just below the two farmhouses on the hillside, there’s a tiny, tilted green flag and—”