An E-Class Mercedes sedan waited in the Borgo Santo Spirito. Gabriel was behind the wheel; Chiara, in the passenger seat. When Donati slid into the back, the car shot forward. Several pedestrians, including a curial priest whom Donati knew in passing, scurried for cover.

“Is there a problem?” he asked.

Gabriel glanced into the rearview mirror. “I’ll know in a few minutes.”

The car swerved to the right, narrowly missing a flock of gray-habited nuns, and raced across the Tiber.

Donati fastened his safety belt and closed his eyes.

God, come to my assistance. Lord, make haste to help me …

THEY SPED NORTH ALONG THE Lungotevere to the Piazza del Popolo, then south to Piazza Venezia. Even by Rome’s lofty standards, it was a hair-raising ride. Donati, a veteran of countless papal motorcades, marveled at the skill with which his old friend handled the powerful German-made car, and at the apparent calm with which Chiara occasionally offered directions or advice. Their route was indirect and full of sudden stops and abrupt turns, all designed to reveal the presence of motorized surveillance. In a city like Rome, where scooters were a common form of transport, it was a daunting task. Donati tried to be of help, but in time he gave up and watched the graffiti-spattered buildings and mountain ranges of uncollected garbage flashing past his window. Veronica was right. Rome was beautiful, but it was gross.

By the time they reached Ostiense, a chaotic working-class quarter in Municipio VIII, Gabriel appeared satisfied they were not being followed. He made his way to the A90, Rome’s orbital motorway, and headed north to the E35 Autostrada, a toll road stretching the length of Italy to the Swiss border.

Donati eased his grip on the armrest. “Do you mind telling me where we’re going?”

Gabriel pointed toward a blue-and-white sign at the side of the road.

Donati permitted himself a brief smile. It had been a long time since he had been to Florence.

UNIT 8200 HAD LOCATED THE phone on the Florence cellular grid shortly before five that morning. It was north of the Arno in San Marco, the quarter of the city where the Medici, the banking dynasty that transformed Florence into the artistic and intellectual heart of Europe, had stabled their menagerie of giraffes, elephants, and lions. Thus far, the Unit had been unable to penetrate the device and gain control of its operating system. It was merely monitoring the phone’s approximate position using geolocation techniques.

“In layman’s language, please?” asked Donati.

“Once we’re inside a phone, we can listen to the owner’s calls, read his e-mail and text messages, and monitor his browsing on the Internet. We can even take photographs and videos with the camera and use the microphone as a listening device.”

“It’s as though you’re God.”

“Not quite, but we certainly have the power to peer into someone’s soul. We can learn their darkest fears and their deepest desires.” Gabriel gave a rueful shake of his head. “The telecommunications industry and their friends in Silicon Valley promised us a brave new world of convenience, all at our fingertips. They told us not to worry, our secrets would be safe. None of it was true. They intentionally lied to us. They stole our privacy. And in the process, they’ve ruined everything.”

“Everything?”

“Newspapers, movies, books, music … everything.”

“I never knew you were such a Luddite.”

“I’m an art restorer who specializes in Italian Old Masters. I’m a charter member of the club.”

“And yet you carry a mobile phone.”

“A very special mobile phone. Even my friends at the American NSA can’t crack it.”

Donati held up a Nokia 9 Android. “And mine?”

“I’d feel much better if you threw it out the window.”

“My life is on this phone.”

“Therein lies the problem, Excellency.”

At Gabriel’s request, Donati surrendered his phone to Chiara. After switching off the power, she removed the SIM card and the battery and placed both in her handbag. The soulless chassis she returned to Donati.

“I feel better already.”

They stopped for coffee at an Autogrill near Orvieto and reached the outskirts of Florence a few minutes after noon. The Zona Traffico Limitato signs were flashing red. Gabriel left the Mercedes in a public car park near the Basilica di Santa Croce, and together they set out toward San Marco.

According to the blue light on Gabriel’s phone, Janson’s device was just west of the San Marco Museum, probably on the Via San Gallo. Unit 8200 had cautioned that the geolocation plot was accurate only to about forty meters, which meant the phone could also be on the Via Santa Reparata or the Via della Ruote. All three streets were lined with small discount hotels and hostels. Gabriel counted at least fourteen such establishments where Niklaus Janson might have found lodging.

The exact spot upon which the blue dot rested corresponded to the address of a hotel appropriately called the Piccolo. Directly across the street was a restaurant where Gabriel lunched in the manner of a man for whom time was of no consequence. Donati, his phone reassembled and operational, dined on the Via Santa Reparata; Chiara, around the corner on the Villa della Ruote.

Gabriel and Chiara each had a copy of Janson’s official Swiss Guard photograph on their phones. It showed a serious young man with short hair and small dark eyes set within an angular face. Trustworthy, thought Gabriel, but by no means a saint. Janson’s file listed his height as the metric equivalent of about six feet. His weight was seventy-five kilograms, or one hundred and sixty-five pounds.

By three fifteen they had seen no sign of him. Chiara moved to the restaurant opposite the Hotel Piccolo; Donati, to the Villa della Ruote. On the Via Santa Reparata, Gabriel spent much of the time staring at his phone, exhorting the winking blue light into movement. At five o’clock, twelve hours after its initial discovery, its position was unchanged. Despairing, Gabriel conjured an image of an unplugged smartphone expiring slowly in an abandoned room littered with empty takeaway cartons.

A text message from Chiara lifted his spirits. I’m now fifteen pounds overweight. Maybe we should just call the number.

What if he was involved?

I thought you said we weren’t there yet.

We aren’t. But we’re getting closer by the minute.

At half past five they changed positions a second time. Gabriel went to a restaurant on the Villa della Ruote. He took a table on the street and picked at a plate of spaghetti pomodoro without appetite.

“If it’s not to your liking,” said the waiter, “I can bring you something else.”

Gabriel ordered a double espresso, his fifth of the afternoon, and with a slightly trembling hand reached for his phone. There was another message from Chiara.

Twenty pounds. I’m begging you, please call him.

Gabriel was sorely tempted. Instead, he watched the tourists trudging back to their hotels after a long day sampling the delights of Florence. There were four hotels along the street. The inappropriately named Grand Hotel Medici was adjacent to the restaurant, directly in Gabriel’s line of sight.

He checked the time on his phone. It was six fifteen. Then he checked the position of the light on the geolocation graph and detected what appeared to be the faintest trace of a wobble. Thirty additional seconds of rigorous observation confirmed his suspicion. The light was definitely moving.