Gabriel Allon had confronted evil in many forms: terrorists, murderous Russian arms dealers, professional assassins who shed the blood of strangers for briefcases filled with cash. But none could compare to the genocidal evil of the men and women who had carried out the single greatest act of mass murder in history. They had been a constant if unacknowledged presence inside Gabriel's childhood home in the Jezreel Valley of Israel. And now that night had fallen over Amsterdam, they had crept into the suite at the Ambassade Hotel. Unable to bear their company any longer, he stood abruptly and informed Eli Lavon and Chiara that he needed to continue the conversation outside. They drifted along the banks of the Herengracht through yellow lamplight, Gabriel and Lavon shoulder to shoulder, Chiara trailing several paces behind.

"She's too close."

"She's not tailing us, Eli. She's just watching our back."

"It doesn't matter. She's still too close."

"Shall we stop so you can give her a bit of instruction?"

"She never listens to me. She's unbelievably stubborn. And far too pretty for street work." Lavon gave Gabriel a sideways glance. "I'll never understand what she saw in a fossil like you. It must have been your natural charm and cheerful disposition."

"You were about to tell me more about Kurt Voss."

Lavon paused to allow a bicycle to pass. It was ridden by a young woman who was steering with one hand and sending a text message with the other. Lavon gave a fleeting smile, then resumed his lecture.

"Keep one thing in mind, Gabriel. We know a great deal about Voss now, but in the aftermath of the war we barely knew the bastard's name. And by the time we fully understood the true nature of his crimes, he'd disappeared."

"Where did he go?"

"Argentina."

"How did he get there?"

"How do you think?"

"The Church?"

"But of course."

Gabriel shook his head slowly. To this day, historians bitterly debated whether Pope Pius XII, the controversial wartime pontiff, had helped the Jews or turned a blind eye to their suffering. But it was Pius's actions after the war that Gabriel found most damning. The Holy Father never uttered a single word of sorrow or regret over the murder of six million human beings and seemed far more concerned about the perpetrators of the crime than its victims. Not only was the pope an outspoken critic of the Nuremburg trials, he allowed the good offices of the Vatican to be used for one of history's greatest mass flights from justice. Known as the Vatican ratline, it helped hundreds, if not thousands, of Nazi war criminals to escape to sanctuaries in South America and the Middle East.

"Voss got to Rome with the help of old friends from the SS. Occasionally, he would stay in small inns or safe houses, but for the most part he found shelter in Franciscan monasteries and convents."

"And after he arrived?"

"He stayed at a lovely old villa at Number 23 Via Piave. An Austrian priest, Monsignor Karl Bayer, took very good care of him while the Pontifical Commission of Assistance saw to his travel arrangements. Within a few days, he had a Red Cross passport in the name of Rudolf Seibel and a landing permit for Argentina. On May 25, 1949, he boarded the North King in Genoa and set sail for Buenos Aires."

"The ship sounds familiar."

"It should. There was another passenger on board who'd also received help from the Vatican. His Red Cross passport identified him as Helmut Gregor. His real name was—"

"Josef Mengele."

Lavon nodded. "We don't know whether the two men ever met during the crossing. But we do know that Voss's arrival went more smoothly than Mengele's. Apparently, the Angel of Death described himself to immigration officials as a technician, but his luggage was filled with medical files and blood samples from his time at Auschwitz."

"Did Voss have anything interesting in his luggage?"

"You mean something like a Rembrandt portrait?" Lavon shook his head. "As far as we know, Voss came to the New World empty-handed. He listed his occupation as bellman and was admitted to the country without delay. His mentor, Eichmann, arrived a year later."

"It must have been quite a reunion."

"Actually, they didn't get on terribly well in Argentina. They met for coffee a few times at the ABC Cafe in downtown Buenos Aires, but Voss apparently didn't care for Eichmann's company. Eichmann had spent several years in hiding, working as a lumber-jack and a farmer. He was no longer a young god who held the fate of millions in the palm of his hand. He was a common laborer in need of work. And he was seething with bitterness."

"And Voss?"

"Unlike Eichmann, he had a formal education. Within a year, he was working as a lawyer in a firm that catered to the German community in Argentina. In 1955, his wife and son were smuggled out of Germany, and the family was reunited. By all accounts, Kurt Voss lived a rather ordinary but comfortable middle-class life in the Palermo district of Buenos Aires until his death in 1982."

"Why wasn't he ever arrested?"

"Because he had powerful friends. Friends in the secret police. Friends in the army. After we grabbed Eichmann in 1960, he went underground for a few months. But for the most part, the man who put Lena Herzfeld's family on a train to Auschwitz lived out his life without fear of arrest or extradition."

"Did he ever publicly talk about the war?"

Lavon gave a faint smile. "You might find this difficult to believe, but Voss actually granted an interview to Der Spiegel a few years before his death. As you might expect, he maintained his innocence to the end. He denied ever deporting anyone. He denied ever killing anyone. And he denied ever stealing a thing."

"So what happened to all that money Voss didn't steal?"

"There's general consensus among Holocaust restitution experts, myself included, that he was never able to get it out of Europe. In fact, the exact fate of Kurt Voss's fortune is regarded as one of the great unsolved mysteries of the Holocaust."

"Any ideas where it might be?"

"Come now, Gabriel. You don't need me to tell you that."

"Switzerland?"

Lavon nodded. "As far as the SS was concerned, the entire country was a giant safe-deposit box. We know from American OSS records that Voss was a frequent visitor to Zurich throughout the war. Unfortunately, we don't know who he was meeting with or where he did his private banking. While I was in Vienna, I worked with a family whose ancestors had been fleeced by Voss at the Zentralstelle in 1938. I spent years knocking on doors in Zurich searching for that money."

"And?"

"Not a trace, Gabriel. Not a single trace. As far as the Swiss banking industry is concerned, Kurt Voss never existed. And neither did his looted fortune."