Robert Langdon.

Sienna Brooks.

Zero doubt.

Brüder turned his attention to the map of the Boboli Gardens, which was spread out on the hood. They made a poor choice, he thought, eyeing the garden layout. While it was sprawling and intricate, with plenty of hiding places, the gardens also appeared to be surrounded on all sides by high walls. The Boboli Gardens were the closest thing to a natural killbox that Brüder had ever seen in the field.

They’ll never get out.

“Local authorities are sealing all exits,” the agent said. “And commencing a sweep.”

“Keep me informed,” Brüder said.

Slowly, he raised his eyes to the van’s thick polycarbonate window, beyond which he could see the silver-haired woman seated in the back of the vehicle.

The drugs they had given her had definitely dulled her senses — more than Brüder had imagined. Nonetheless, he could tell by the fearful look in her eyes that she still had a firm grasp on precisely what was going on.

She does not look happy, Brüder thought. Then again, why would she?

A spire of water shot twenty feet in the air.

Langdon watched it fall gently back to earth and knew they were getting close. They had reached the end of La Cerchiata’s leafy tunnel and dashed across an open lawn into a grove of cork trees. Now they were looking out at the Boboli’s most famous spouting fountain — Stoldo Lorenzi’s bronze of Neptune clutching his three-pronged trident. Irreverently known by locals as “The Fountain of the Fork,” this water feature was considered the central point of the gardens.

Sienna stopped at the edge of the grove and peered upward through the trees. “I don’t see the drone.”

Langdon no longer heard it either, and yet the fountain was quite loud.

“Must have needed to refuel,” Sienna said. “This is our chance. Which way?”

Langdon led her to the left, and they began descending a steep incline. As they emerged from the trees, the Pitti Palace came into view.

“Nice little house,” Sienna whispered.

“Typical Medici understatement,” he replied wryly.

Still almost a quarter mile away, the Pitti Palace’s stone facade dominated the landscape, stretching out to their left and right. Its exterior of bulging, rusticated stonework lent the building an air of unyielding authority that was further accentuated by a powerful repetition of shuttered windows and arch-topped apertures. Traditionally, formal palaces were situated on high ground so that anyone in the gardens had to look uphill at the building. The Pitti Palace, however, was situated in a low valley near the Arno River, meaning that people in the Boboli Gardens looked downhill at the palace.

This effect was only more dramatic. One architect had described the palace as appearing to have been built by nature herself … as if the massive stones in a landslide had tumbled down the long escarpment and landed in an elegant, barricade-like pile at the bottom. Despite its less defensible position in the low ground, the solid stone structure of the Pitti Palace was so imposing that Napoleon had once used it as a power base while in Florence.

“Look,” Sienna said, pointing to the nearest doors of the palace. “Good news.”

Langdon had seen it, too. On this strange morning, the most welcome sight was not the palace itself, but the tourists streaming out of the building into the lower gardens. The palace was open, which meant that Langdon and Sienna would have no trouble slipping inside and passing through the building to escape the gardens. Once outside the palace, Langdon knew they would see the Arno River to their right, and beyond that, the spires of the old city.

He and Sienna kept moving, half jogging now down the steep embankment. As they descended, they traversed the Boboli Amphitheater — the site of the very first opera performance in history — which lay nestled like a horseshoe on the side of a hill. Beyond that, they passed the obelisk of Ramses II and the unfortunate piece of “art” that was positioned at its base. The guidebooks referred to the piece as “a colossal stone basin from Rome’s Baths of Caracalla,” but Langdon always saw it for what it truly was — the world’s largest bathtub. They really need to put that thing somewhere else.

They finally reached the rear of the palace and slowed to a calm walk, mixing inconspicuously with the first tourists of the day. Moving against the tide, they descended a narrow tunnel into the cortile, an inner courtyard where visitors were seated enjoying a morning espresso in the palace’s makeshift café. The smell of fresh-ground coffee filled the air, and Langdon felt a sudden longing to sit down and enjoy a civilized breakfast. Today’s not the day, he thought as they pressed on, entering the wide stone passageway that led toward the palace’s main doors.

As they neared the doorway, Langdon and Sienna collided with a growing bottleneck of stalled tourists who seemed to be assembling in the portico to observe something outside. Langdon peered through the crowd to the area in front of the palace.

The Pitti’s grand entrance was as blunt and unwelcoming as he recalled it. Rather than a manicured lawn and landscaping, the front yard was a vast expanse of pavement that stretched across an entire hillside, flowing down to the Via dei Guicciardini like a massive paved ski slope.

At the bottom of the hill, Langdon now saw the reason for the crowd of onlookers.

Down in Piazza dei Pitti, a half-dozen police cars had streamed in from all directions. A small army of officers were advancing up the hill, unholstering their weapons and fanning out to secure the front of the palace.

As the police entered the Pitti Palace, Sienna and Langdon were already on the move, retracing their steps through the interior of the palace and away from the arriving police. They hurried through the cortile and past the café, where a buzz was spreading, tourists rubbernecking in an attempt to locate the source of the commotion.

Sienna was amazed the authorities had found them so quickly. The drone must have disappeared because it had already spotted us.

She and Langdon found the same narrow tunnel through which they had descended from the gardens and without hesitation plunged back into the passageway and bounded up the stairs. The end of the staircase banked left along a high retaining wall. As they dashed along the wall, it grew shorter beside them, until finally they could see over it into the vast expanse of the Boboli Gardens.

Langdon instantly grabbed Sienna’s arm and yanked her backward, ducking out of sight behind the retaining wall. Sienna had seen it, too.

Three hundred yards away, on the slope above the amphitheater, a phalanx of police descended, searching groves, interviewing tourists, coordinating with one another on handheld radios.

We’re trapped!

Sienna had never imagined, when she and Robert Langdon first met, that it would lead to this. This is more than I bargained for. When Sienna had left the hospital with Langdon, she thought they were fleeing a woman with spiked hair and a gun. Now they were running from an entire military team and the Italian authorities. Their chances of escape, she was now realizing, were almost zero.

“Is there any other way out?” Sienna demanded, short of breath.

“I don’t think so,” Langdon said. “This garden is a walled city, just like …” He paused suddenly, turning and looking east. “Just like … the Vatican.” A strange glint of hope flickered across his face.

Sienna had no idea what the Vatican had to do with their current predicament, but Langdon suddenly began nodding, gazing east along the back of the palace.

“It’s a long shot,” he said, hustling her along with him now. “But there might be a different way to get out of here.”