Sienna looked puzzled by this last point.

“Smell this,” Langdon said, raising the mask to her face like a priest offering Communion.

Sienna cringed. “Gesso smells like a wet dog?”

“Not all gesso. Regular gesso smells like chalk. Wet dog is acrylic gesso.”

“Meaning …?”

“Meaning it’s water soluble.”

Sienna cocked her head, and Langdon could sense the wheels turning. She shifted her gaze slowly to the mask and then suddenly back to Langdon, her eyes wide. “You think there’s something under the gesso?”

“It would explain a lot.”

Sienna immediately gripped the hexagonal wooden font covering and rotated it partway off, exposing the water below. She grabbed a fresh linen towel and plunged it into the baptismal water. Then she held out the dripping cloth for Langdon. “You should do it.”

Langdon placed the mask facedown in his left palm and took the wet linen. Shaking out the excess water, he began dabbing the damp cloth on the inside of Dante’s forehead, moistening the area with the seven calligraphic Ps. After several dabs with his index finger, he redipped the cloth in the font and continued. The black ink began smearing.

“The gesso is dissolving,” he said excitedly. “The ink is coming off with it.”

As he performed the process a third time, Langdon began speaking in a pious and somber monotone, which resonated in the baptistry. “Through baptism, the Lord Jesus Christ has freed you from sin and brought you to new life through water and the Holy Spirit.”

Sienna stared at Langdon like he’d lost his mind.

He shrugged. “It seemed appropriate.”

She rolled her eyes and turned back to the mask. As Langdon continued applying water, the original plaster beneath the gesso became visible, its yellowish hue more in keeping with what Langdon would have expected from an artifact this old. When the last of the Ps had disappeared, he dried the area with a clean linen and held the mask up for Sienna to observe.

She gasped out loud.

Precisely as Langdon had anticipated, there was indeed something hidden beneath the gesso—a second layer of calligraphy—nine letters written directly onto the pale yellow surface of the original plaster.

This time, however, the letters formed a word.

CHAPTER 58

“ ‘Possessed’?” Sienna demanded. “I don’t understand.”

I’m not sure I do either. Langdon studied the text that had materialized beneath the seven Ps—a single word emblazoned across the inside of Dante’s forehead.

“As in … possessed by the devil?” Sienna asked.

Possibly. Langdon turned his gaze overhead to the mosaic of Satan consuming the wretched souls who had never been able to purge themselves of sin. Dante … possessed? It didn’t seem to make much sense.

“There’s got to be more,” Sienna contended, taking the mask from Langdon’s hands and studying it more closely. After a moment she began nodding. “Yes, look at the ends of the word … there’s more text on either side.”

Langdon looked again, now seeing the faint shadow of additional text showing through the moist gesso at either end of the word possessed.

Eagerly, Sienna grabbed the cloth and continued dabbing around the word until more text materialized, written on a gentle curve.

O you possessed of sturdy intellect

Langdon let out a low whistle. “ ‘O, you possessed of sturdy intellect … observe the teachings hidden here … beneath the veil of verses so obscure.’ ”

Sienna stared at him. “I’m sorry?”

“It’s taken from one of the most famous stanzas of Dante’s Inferno,” Langdon said excitedly. “It’s Dante urging his smartest readers to seek the wisdom hidden within his cryptic verse.”

Langdon often cited this exact line when teaching literary symbolism; the line was as close an example as existed to an author waving his arms wildly and shouting: “Hey, readers! There is a symbolic double meaning here!”

Sienna began rubbing the back of the mask, more vigorously now.

“Careful with that!” Langdon urged.

“You’re right,” Sienna announced, zealously wiping away gesso. “The rest of Dante’s quote is here—just as you recalled it.” She paused to dip the cloth back in the font and rinse it out.

Langdon looked on in dismay as the water in the baptismal font turned cloudy with dissolved gesso. Our apologies to San Giovanni, he thought, uneasy that this sacred font was being used as a sink.

When Sienna raised the cloth from the water, it was dripping. She barely wrung it out before placing the soggy cloth in the center of the mask and swishing it around as if she were cleaning a soup bowl.

“Sienna!” Langdon admonished. “That’s an ancient—”

“The whole back side has text!” she announced as she scoured the inside of the mask. “And it’s written in …” She paused, cocking her head to the left and rotating the mask to the right, as if trying to read sideways.

“Written in what?” Langdon demanded, unable to see.

Sienna finished cleaning the mask and dried it off with a fresh cloth. Then she set it down in front of him so they could both study the result.

When Langdon saw the inside of the mask, he did a double take. The entire concave surface was covered in text, what had to be nearly a hundred words. Beginning at the top with the line O you possessed of sturdy intellect, the text continued in a single, unbroken line … curling down the right side of the mask to the bottom, where it turned upside down and continued back across the bottom, returning up the left side of the mask to the beginning, where it repeated a similar path in a slightly smaller loop.

The path of the text was eerily reminiscent of Mount Purgatory’s spiraling pathway to paradise. The symbologist in Langdon instantly identified the precise spiral. Symmetrical clockwise Archimedean. He had also noted that the number of revolutions from the first word, O, to the final period in the center was a familiar number.

Nine.

Barely breathing, Langdon turned the mask in slow circles, reading the text as it curled ever inward around the concave bowl, funneling toward the center.

“The first stanza is Dante, almost verbatim,” Langdon said. “ ‘O you possessed of sturdy intellect, observe the teaching that is hidden here … beneath the veil of verses so obscure.’ ”

“And the rest?” Sienna pressed.

Langdon shook his head. “I don’t think so. It’s written in a similar verse pattern, but I don’t recognize the text as Dante’s. It looks like someone is imitating his style.”

“Zobrist,” Sienna whispered. “It has to be.”

Langdon nodded. It was as good a guess as any. Zobrist, after all, by altering Botticelli’s Mappa dell’Inferno, had already revealed his proclivity for collaborating with the masters and modifying great works of art to suit his needs.

“The rest of the text is very strange,” Langdon said, again rotating the mask and reading inward. “It talks about … severing the heads from horses … plucking up the bones of the blind.” He skimmed ahead to the final line, which was written in a tight circle at the very center of the mask. He drew a startled breath. “It also mentions ‘bloodred waters.’ ”

Sienna’s eyebrows arched. “Just like your visions of the silver-haired woman?”

Langdon nodded, puzzling over the text. The bloodred waters … of the lagoon that reflects no stars?

“Look,” she whispered, reading over his shoulder and pointing to a single word partway through the spiral. “A specific location.”

Langdon’s eyes found the word, which he had skimmed over on his first pass. It was the name of one of the most spectacular and unique cities in the world. Langdon felt a chill, knowing it also happened to be the city in which Dante Alighieri famously became infected with the deadly disease that killed him.

Venice.

Langdon and Sienna studied the cryptic verses in silence for several moments. The poem was disturbing and macabre, and hard to decipher. Use of the words doge and lagoon confirmed for Langdon beyond any doubt that the poem was indeed referencing Venice—a unique Italian water-world city made up of hundreds of interconnected lagoons and ruled for centuries by a Venetian head of state known as a doge.

At a glance, Langdon could not discern exactly where in Venice this poem was pointing, but it definitely seemed to be urging the reader to follow its directions.

Place thine ear to the ground, listening for the sounds of trickling water.

“It’s pointing underground,” Sienna said, reading along with him.

Langdon gave an uneasy nod as he read the next line.

Follow deep into the sunken palace … for here, in the darkness, the chthonic monster waits.

“Robert?” Sienna asked uneasily. “What kind of monster?”

“Chthonic,” Langdon replied. “The c-h is silent. It means ‘dwelling beneath the earth.’ ”

Before Langdon could continue, the loud clunk of a dead bolt echoed across the baptistry. The tourist entrance had apparently just been unlocked from outside.

“Grazie mille,” said the man with the rash on his face. A thousand thanks.

The baptistry docent nodded nervously as he pocketed the five hundred dollars cash and glanced around to make sure nobody was watching.

“Cinque minuti,” the docent reminded, discreetly swinging open the unbolted door just wide enough for the man with the rash to slip inside. The docent closed the door, sealing the man inside and blocking out all sound from outside. Five minutes.

Initially the docent had refused to take pity on the man who claimed to have come all the way from America to pray at the Baptistry of San Giovanni in hopes of curing his terrible skin disease. Eventually, though, he had been inspired to become sympathetic, aided no doubt by an offer of five hundred dollars for five minutes alone in the baptistry … combined with the growing fear that this contagious-looking person would stand there beside him for the next three hours until the building opened.

Now, as he moved stealthily into the octagonal sanctuary, the man felt his eyes drawn reflexively upward. Holy shit. The ceiling was like nothing he’d ever seen. A three-headed demon stared down directly at him, and he quickly lowered his gaze to the floor.

The space appeared to be deserted.

Where the hell are they?

As the man scanned the room, his eyes fell on the main altar. It was a massive rectangular block of marble, set back in a niche, behind a barrier of stanchions and swags to keep spectators away.

The altar appeared to be the only hiding place in the entire room. Moreover, one of the swags was swinging slightly … as if it had just been disturbed.

Behind the altar, Langdon and Sienna crouched in silence. They had barely had time to collect the dirty towels and straighten the font cover before diving out of sight behind the main altar, with the death mask carefully in tow. The plan was to hide here until the room filled up with tourists, and then discreetly exit among the crowd.

The baptistry’s north door had definitely just been opened—at least for a moment—because Langdon had heard sounds emanating from the piazza, but then just as abruptly, the door had been closed, and all had gone quiet again.

Now, back in the silence, Langdon heard a single set of footsteps moving across the stone floor.

A docent? Checking the room before opening it to tourists later today?

He had not had time to extinguish the spotlight over the baptismal font and wondered if the docent would notice. Apparently not. The footsteps were moving briskly in their direction, pausing just in front of the altar at the swag that Langdon and Sienna had just vaulted over.

There was a long silence.

“Robert, it’s me,” a man’s voice said angrily. “I know you’re back there. Get the hell out here and explain yourself.”

CHAPTER 59

There’s no point in pretending I’m not here.

Langdon motioned for Sienna to remain crouched safely out of sight, holding the Dante death mask, which he had resealed in the Ziploc bag.

Then, slowly, Langdon rose to his feet. Standing like a priest behind the altar of the baptistry, Langdon gazed out at his congregation of one. The stranger facing him had sandy-brown hair, designer glasses, and a terrible rash on his face and neck. He scratched nervously at his irritated neck, his swollen eyes flashing daggers of confusion and anger.

“You want to tell me what the hell you’re doing, Robert?!” he demanded, stepping over the swag and advancing toward Langdon. His accent was American.

“Sure,” Langdon replied politely. “But first, tell me who you are.”

The man stopped short, looking incredulous. “What did you say?!”

Langdon sensed something vaguely familiar in the man’s eyes … his voice, too, maybe. I’ve met him … somehow, somewhere. Langdon repeated his question calmly. “Please tell me who you are and how I know you.”

The man threw up his hands in disbelief. “Jonathan Ferris? World Health Organization? The guy who flew to Harvard University and picked you up!?”

Langdon tried to process what he was hearing.

“Why haven’t you called in?!” the man demanded, still scratching at his neck and cheeks, which looked red and blistered. “And who the hell is the woman I saw you come in here with?! Is she the one you’re working for now?”

Sienna scrambled to her feet beside Langdon and immediately took charge. “Dr. Ferris? I’m Sienna Brooks. I’m also a doctor. I work here in Florence. Professor Langdon was shot in the head last night. He has retrograde amnesia, and he doesn’t know who you are or what happened to him over the last two days. I’m here because I’m helping him.”

As Sienna’s words echoed through the empty baptistry, the man cocked his head, puzzled, as if her meaning had not quite registered. After a dazed beat, he staggered back a step, steadying himself on one of the stanchions.