J ulian Isherwood had examined paintings in cellars and salesrooms, in bank vaults and bonded warehouses, and on one occasion while engaged in the act of love with the widow of a wealthy collector.

But never once during his storied career had he assessed a work of art while airborne.

He supposed there was a first time for everything, even at his advanced age.

There were five other passengers aboard the Dassault—four security goons and a well-dressed man in his late fifties with a sharp-featured face, olive-complected skin, and thinning hair combed closely to his scalp.

Julian extended his hand in greeting, but the man demanded his mobile phone instead.

He did so in Italian-accented English. Julian surrendered the device under protest, then watched it disappear into a black nylon pouch.

A pretty cabin attendant presented him with a glass of prosecco.

From Peter van de Velde he received a muted apology.

“Sorry, Julian. My partner is a careful man.”

“Does he have a name, your partner?”

“Not one he wishes to divulge at this time.”

Van de Velde waited until the plane had leveled off somewhere over the Netherlands before finally fetching a shallow art transport case from the cabin’s aft compartment.

Inside, covered by two sheets of protective glassine paper, was a portrait of a beautiful fair-haired woman gazing directly at the viewer over her left shoulder—78 by 56 centimeters, or thereabouts.

Van de Velde, after first pulling on a pair of protective white gloves, removed the panel from the case and laid it carefully on the cabin’s table.

“Do you recognize her, Julian?”

“Yes, of course.”

Van de Velde offered him a pair of gloves. “Have a closer look. I think you’ll see something special.”

Julian pulled on the gloves and, grasping the painting with both hands, turned it over and had a look at the back.

The original walnut panel had been adhered to an oak panel, perhaps nineteenth century, with three scratched and dented horizontal supports—one along the top edge of the painting, one across the center, and one at the bottom.

There were no stamps or markings of any kind, nothing that might identify a previous owner.

Julian, inhaling deeply, thought he detected the faintest aroma of fresh rabbit skin glue.

He laid the panel on the table and examined the image in the sunlight streaming through the Dassault’s windows.

Typically he used a handheld ultraviolet torch to expose the overpainting of previous restorations, but in this case it wasn’t necessary; a large portion of the panel’s surface was covered in recently applied inpainting.

The woman’s heavy-lidded left eye, however, had received no retouching.

When Julian viewed the iris and pupil through a magnifying glass, he feared for an instant that his heart had ceased to beat.

“What do you think?” asked Van de Velde.

Julian didn’t dare answer truthfully, for his anger was at that moment incandescent. Instead he lowered the magnifying glass and waited for the painting to speak to him. It was quite talkative indeed.

“It’s a lovely picture of obvious quality, Peter. But one wonders how it ended up in an Amsterdam flea market.”

“You should have seen it before it was restored. There were several layers of old overpaint and a gloppy coat of brown varnish. At first I thought it was Dutch or Flemish. But I no longer believe that’s the case.”

“Nor do I,” said Julian.

“Is it Italian?”

“Almost certainly.”

“Florentine School?”

“Could be, Peter. But where are we going with this?”

“My partner and I were wondering...” He left the thought unfinished.

“Whether I thought it was a Leonardo?”

Van de Velde nodded.

“Come now, Peter. You don’t really expect me to answer that question after spending less than five minutes with the picture.”

“But you were clearly impressed by it. I saw it in your eyes.”

“I agree that the brushwork resembles Leonardo’s, but that does not mean it is his. Furthermore, there is nothing in the historical record to suggest he ever used the silverpoint preparatory sketch of the young woman to produce an oil painting.”

“There’s nothing about the Salvator Mundi either.”

Julian, with his silence, conceded the point.

He had yet to look up from the painting.

She had been horribly mistreated, the beautiful young woman with mismatched pupils.

Julian, at that instant, resolved to rescue her.

But how? Personal heroics were not his calling card, especially at thirty thousand feet.

The occasional act of professional duplicity in service of a noble cause was more his style.

“There’s a simple solution, you know.”

“What’s that?” asked Van de Velde.

“Let me take the picture back to London. I’ll show it to the curators at the National Gallery and subject it to rigorous scientific analysis. I’ll also hire someone to research the painting’s provenance.”

“Who’s going to pay for all this?”

“Isherwood Fine Arts.”

“And what would Isherwood Fine Arts expect in return?”

“If my work results in the discovery of a lost painting by Leonardo, it will be well worth the money.”

Van de Velde turned to his nameless partner, who shook his head slowly. “Sorry, Mr. Isherwood, but the painting stays with us.”

“In that case, you leave me no choice but to buy it.”

The man smiled. “The bidding starts at two hundred and fifty million.”

“If it’s a Leonardo, it’s a steal at that price.” Julian checked the time. “Mind taking me back to Schiphol now? With a bit of luck, I can still make my flight to London.”

***

The Dassault Falcon deposited Julian not at Amsterdam’s Schiphol Airport but at Le Bourget in Paris. His hosts had been good enough to arrange another chauffeured car. He rang Sarah during the drive to the Gare du Nord. She seemed genuinely relieved to hear the sound of his voice.

“I was beginning to think you’d fallen off a cliff.”

“There are no cliffs in Holland, petal. That said, my day took a most unexpected turn.”

“I’m afraid to ask where you are.”

“The Eighteenth Arrondissement of Paris.”

“Could be worse.”

“Much,” he agreed.

“Did you see it?”

“I did indeed.”

“And?”

“We should talk when I get back to London.”

“You know where to find me,” she said, and rang off.

He arrived at the Gare du Nord in time to catch the two thirty Eurostar and strode through the door of Wiltons a few minutes before five o’clock. As misfortune would have it, he collided with tubby Oliver Dimbleby, a thoroughly disreputable Old Masters dealer from Bury Street.

“Julie!” he purred. “Haven’t seen you in days. Where in God’s name have you been?”

“A sanatorium, if you must know.”

“Nothing serious, I hope.”

“Emotional exhaustion.”

“I hear it’s fatal.”

“They’ve given me three weeks to live.”

The usual crowd was arrayed along the bar.

Tweedy Jeremy Crabbe from Bonhams, suntanned Simon Mendenhall from Christie’s, the learned Niles Dunham of the National Gallery.

Roddy Hutchinson, universally regarded as the most unscrupulous dealer in all of St. James’s, was baring his soul to the impossibly beautiful former fashion model who now owned a successful contemporary art gallery in King Street.

Nicky Lovegrove, art adviser to the vastly rich, was whispering sweet nothings into the ear of Amelia March, who was scribbling furiously in her reporter’s notebook.

Julian peered over her shoulder. “What are you working on?”

“Your obituary.”

“Please treat me kindly. ”

“Don’t I always?”

Sarah and Gabriel were seated at the bar’s corner table. Sarah was drinking her usual three-olive Belvedere martini, Gabriel a glass of white wine. Julian lifted the bottle from the ice bucket and scrutinized the label.

“Domaine Laroche Grand Cru Chablis.”

“Sarah’s treat,” said Gabriel. “A little something to celebrate the successful completion of your mission.”

Julian pulled up a chair and settled wearily into it. “My mission, as you call it, was far more harrowing than previously advertised. Especially the unscheduled private flight from Amsterdam to Paris. Don’t get me wrong, the plane was lovely. But I didn’t much care for the other passengers.”

“How many were there?”

“Five,” replied Julian while pouring himself a glass of the Chablis. “Including Peter van de Velde’s so-called partner. Looked like a perfectly presentable businessman, but I doubt that was the case.”

“Italian, was he?”

“Definitely.”

“And the others?”

“They were the businessman’s bodyguards. Or perhaps the painting’s.”

“Is it a Leonardo?”

“Many careers have been ruined by mistaken attributions to Leonardo...”

“But?”

“I believe it’s him.”

“What sort of condition is it in?”

“Dreadful. I have a right mind to go back to Amsterdam and wring Peter van de Velde’s neck.”

“In all likelihood, Van de Velde had very little to do with it. He’s merely fronting the deal for the men who stole it from the Vatican.”

“But he knows the other players, though.”

“Some of them,” Gabriel admitted. “But he doesn’t have possession of the painting. And if we confront him, we will lose our greatest advantage.”

“Which is?”

“The men who stole the Leonardo are under the impression that they’ve gotten away with the greatest art heist in history. And their overconfidence has led them to make two critical mistakes.”

“The first?”

“Inviting you to Amsterdam.”

“And the second?”

It was Sarah, martini glass to her lips, who answered. “Putting you on that airplane.”

***

It was a mistake, Sarah continued, because international convention requires all civilian aircraft to have a unique alphanumeric identification code prominently displayed on their exterior.

These codes allow air traffic controllers and airport authorities to track and record the movement of individual planes around the globe.

But private citizens likewise have access to the data, as the CIA discovered when investigative reporters revealed that the Agency was using a fleet of private jets to secretly transfer captured members of al-Qaeda to so-called black sites for enhanced interrogation.

The multibillionaire chairman of a French luxury goods conglomerate had recently unloaded his Bombardier 7500 because he had grown weary of climate activists posting his carbon emissions on social media.

“I should have such problems,” muttered Julian. “But who owns the plane that I was on this morning? ”

“Eiger Air Transport,” replied Sarah.

“A shell company, I assume.”

“But of course. It’s Swiss registered, as is the plane itself. In fact, it headed to Switzerland after dropping you at Le Bourget.”

“Somewhere nice?”

“Lugano,” answered Gabriel. “Your perfectly presentable Italian businessman and his bodyguards then made their way by car to a bank in the Piazza della Riforma, Lugano’s main square.”

“How do you know that?”

“Because they foolishly took Peter van de Velde with him, and I was monitoring his phone.”

“And the name of this bank?”

“SBL PrivatBank SA.”

“Is the Leonardo now hidden in that bank?”

“It might be,” replied Gabriel. “But I have a feeling it’s been on the move of late.”

“Why?”

“The plane’s flight records,” interjected Sarah. “It was in Dubai for three days last week. And the week before, it made stops in Tokyo and Hong Kong.”

“It sounds to me as if they’re showing the painting to prospective buyers. There are any number of extremely wealthy people in the world who would think nothing about plunking down a few hundred million for an authentic Leonardo, regardless of where it came from.”

“Don’t worry,” said Gabriel. “We won’t let that happen.”

“What are we going to do? Break into that bank in Lugano?”

“We’re going to wait for them to make another mistake.”

“And then?”

Gabriel looked at the cast of art world characters lining the bar. “We’ll make our move.”