While Langdon would never consider St. Mark’s a stand-in for the spectacular mosques of Turkey, he did have to admit that one’s passion for Byzantine art could be satisfied with a visit to the secret suite of rooms just off the right transept in this church, in which was hidden the so-called Treasure of St. Mark — a glittering collection of 283 precious icons, jewels, and chalices acquired during the looting of Constantinople.

Langdon was pleased to find the basilica relatively quiet this afternoon. There were still throngs of people, but at least there was room to maneuver. Weaving in and out of various groups, Langdon guided Ferris and Sienna toward the west window, where visitors could step outside and see the horses on the balcony. Despite Langdon’s confidence in their ability to identify the doge in question, he remained concerned about the step they’d have to take after that — locating the doge himself. His tomb? His statue? This would probably require some form of assistance, considering the hundreds of statues housed in the church proper, the lower crypt, and the domed tombs along the church’s north arm.

Langdon spotted a young female docent giving a tour, and he politely interrupted her talk. “Excuse me,” he said. “Is Ettore Vio here this afternoon?”

“Ettore Vio?” The woman gave Langdon an odd look. “Sì, certo, ma—” She stopped short, her eyes brightening. “Lei è Robert Langdon, vero?!” You’re Robert Langdon, aren’t you?

Langdon smiled patiently. “Sì, sono io. Is it possible to speak with Ettore?”

“Sì, sì!” The woman motioned for her tour group to wait a moment and hurried off.

Langdon and the museum’s curator, Ettore Vio, had once appeared together in a short documentary about the basilica, and they had kept in touch ever since. “Ettore wrote the book on this basilica,” Langdon explained to Sienna. “Several of them, actually.”

Sienna still looked strangely unnerved by Ferris, who stayed close while Langdon led the group across the upper register toward the west window, from which the horses could be seen. As they reached the window, the stallions’ muscular hindquarters became visible in silhouette against the afternoon sun. Out on the balcony, wandering tourists enjoyed close contact with the horses as well as a spectacular panorama of St. Mark’s Square.

“There they are!” Sienna exclaimed, moving toward the door that led to the balcony.

“Not exactly,” Langdon said. “The horses we see on the balcony are actually just replicas. The real Horses of St. Mark’s are kept inside for safety and preservation.”

Langdon guided Sienna and Ferris along a corridor toward a well-lit alcove where an identical grouping of four stallions appeared to be trotting toward them out of a backdrop of brick archways.

Langdon motioned admiringly to the statues. “Here are the originals.”

Every time Langdon saw these horses up close, he couldn’t help but marvel at the texture and detail of their musculature. Only intensifying the dramatic appearance of their rippling skin was the sumptuous, golden-green verdigris that entirely covered their surface. For Langdon, seeing these four stallions perfectly maintained despite their tumultuous past was always a reminder of the importance of preserving great art.

“Their collars,” Sienna said, motioning to the decorative breast collars around their necks. “You said those were added? To cover the seam?”

Langdon had told Sienna and Ferris about the strange “severed head” detail he had read about on the ARCA Web site.

“Apparently, yes,” Langdon said, moving toward an informational placard posted nearby.

“Roberto!” a friendly voice bellowed behind them. “You insult me!” Langdon turned to see Ettore Vio, a jovial-looking, white-haired man in a blue suit, with eyeglasses on a chain around his neck, pushing his way through the crowd. “You dare to come to my Venice and not call me?”

Langdon smiled and shook the man’s hand. “I like to surprise you, Ettore. You look good. These are my friends Dr. Brooks and Dr. Ferris.”

Ettore greeted them and then stood back, appraising Langdon. “Traveling with doctors? Are you sick? And your clothing? Are you turning Italian?”

“Neither,” Langdon said, chuckling. “I’ve come for some information on the horses.”

Ettore looked intrigued. “There is something the famous professor does not already know?”

Langdon laughed. “I need to learn about the severing of these horses’ heads for transport during the Crusades.”

Ettore Vio looked as if Langdon had just inquired about the Queen’s hemorrhoids. “Heavens, Robert,” he whispered, “we don’t speak of that. If you want to see severed heads, I can show you the famed decapitated Carmagnola or—”

“Ettore, I need to know which Venetian doge cut off these heads.”

“It never happened,” Ettore countered defensively. “I’ve heard the tales, of course, but historically there is little to suggest that any doge committed—”

“Ettore, please, humor me,” Langdon said. “According to the tale, which doge was it?”

Ettore put on his glasses and eyed Langdon. “Well, according to the tale, our beloved horses were transported by Venice’s most clever and deceitful doge.”

“Deceitful?”

“Yes, the doge who tricked everyone into the Crusades.” He eyed Langdon expectantly. “The doge who took state money to sail to Egypt … but redirected his troops and sacked Constantinople instead.”

Sounds like treachery, Langdon mused. “And what was his name?”

Ettore frowned. “Robert, I thought you were a student of world history.”

“Yes, but the world is large, and history is long. I could use some help.”

“Very well then, a final clue.”

Langdon was going to protest, but he sensed that he’d be wasting his breath.

“Your doge lived for nearly a century,” Ettore said. “A miracle in his day. Superstition attributed his longevity to his brave act of rescuing the bones of Saint Lucia from Constantinople and bringing them back to Venice. Saint Lucia lost her eyes to—”

“He plucked up the bones of the blind!” Sienna blurted, glancing at Langdon, who had just had the same thought.

Ettore gave Sienna an odd look. “In a manner of speaking, I suppose.”

Ferris looked suddenly wan, as if he had not yet caught his breath from the long walk across the plaza and the climb up the stairs.

“I should add,” Ettore said, “that the doge loved Saint Lucia so much because the doge himself was blind. At the age of ninety, he stood out in this very square, unable to see a thing, and preached the Crusade.”

“I know who it is,” Langdon said.

“Well, I should hope so!” Ettore replied with a smile.

Because his eidetic memory was better suited to images rather than uncontextualized ideas, Langdon’s revelation had arrived in the form of a piece of artwork — a famous illustration by Gustave Doré depicting a wizened, blind doge, arms raised high overhead as he incited a gathered crowd to join the Crusade. The name of Doré’s illustration was clear in his mind: Dandolo Preaching the Crusade.

“Enrico Dandolo,” Langdon declared. “The doge who lived forever.”

“Finalmente!” Ettore said. “I fear your mind has aged, my friend.”

“Along with the rest of me. Is he buried here?”

“Dandolo?” Ettore shook his head. “No, not here.”

“Where?” Sienna demanded. “At the Doge’s Palace?”

Ettore took off his glasses, thinking a moment. “Give me a moment. There are so many doges, I can’t recall—”

Before Ettore could finish, a frightened-looking docent came running over and ushered him aside, whispering in his ear. Ettore stiffened, looking alarmed, and immediately hurried over to a railing, where he peered down into the sanctuary below. After a moment he turned back toward Langdon.

“I’ll be right back,” Ettore shouted, and then hurried off without another word.