Joshua M. Greene had decided he was never going to write another book about the Holocaust when he received a call from Ivan Wilzig, urging him to write the story of his father, the Holocaust survivor Siggi Wilzig. It was the summer of 2013 and Greene was blunt.

“I’m done with the Holocaust,” Greene told Ivan. “I’m done with the darkness. I want to work on books that move us toward the light.”Without pause, Wilzig yelled in the phone, “Are you kidding? My father was the light! He was a walking torch! He was a beacon of hope for all immigrants!”

Eight years later, Greene is the first to admit that Ivan Wilzig was right. The proof can be found in Unstoppable (Insight Editions), the newly released, sweeping biography that grew from that phone call. Unstoppable chronicles the life of a man who survived Auschwitz, arrived penniless in New York, and rose to the highest positions in oil and banking. When Wilzig died in 2003, the companies had more than $4 billion in assets. Besides the enormous business success, he was also celebrated as an instrumental force in creating the U.S. Holocaust Memorial Museum.

Greene’s path to the story of Wilzig’s life began in transcripts of his subject’s own words. Prior to his death, the Steven Spielberg Shoah Foundation recorded Wilzig’s testimony, which yielded more than 600 pages when transcribed. In those pages, Greene saw a possibility for connecting Wilzig’s story to a broader story of immigration and the American Dream.

“His accounts were candid, humorous, and insightful. I was learning from the transcripts about a period of history I thought I knew. Yet here were dimensions only an immigrant with Siggi’s volcanic drive could reveal,” Greene says. “By the time I’d finished the transcripts, I was more or less hooked.”

Following liberation from Mauthausen, Wilzig went to work for the U.S. Counterintelligence Corps hunting down former Nazis. Two years later he sailed for New York with barely any money, earning his first dollar in America shoveling snow after a blizzard. Over the years, he worked any job he could take—including in sweatshops—and slowly climbed from poverty to wealth and influence.

Eventually he came to own a major oil company and then ran a full-service commercial bank. At the same time, he worked tirelessly to ensure that the Holocaust was remembered. The first survivor to address cadets at the U.S. Military Academy at West Point, he was also the first person asked by Nobel Laureate Elie

Wiesel to join a presidential commission that later created the Holocaust Museum.

But for Greene, the texture of Wilzig’s stories, happy and sad, was as captivating as the arc of his life. On a forced march to the Mauthausen concentration camp in 1945, Wilzig’s shoelaces broke in the ice and mud. Without shoes, he would die. But in the night, Greene recounts, Wilzig

stripped lengths of bark and then braided them into shoelaces. “That was quintessential Siggi,” Greene says. “He looked for a thread of a solution to the most daunting of challenges—like that thread of bark that saved his life. His attitude was there is always a thread of light to be found, as long as we are willing to lift our heads up and look for it.”

Unstoppable takes on an added importance at a time when the last Holocaust survivors are reaching an older age. With their passing, Greene sees an urgent need for stories like Wilzig’s.

“Remember the footage from January 6 of rioters storming the capitol building, and the man with a sweatshirt with the words ‘Camp Auschwitz’?” Greene says. “Racism and anti-Semitism didn’t die with Hitler in his bunker. They’re alive in America and at the heart of the violence and hatred we’ve been struggling with recently.”

Wilzig’s life is a guide, connecting past and present, and one that Greene has connected with despite his certainty, eight years ago, that he was finished writing about the Holocaust. In Wilzig’s story, Greene says, he found someone whose life was as relatable and funny as it was harrowing and profound. “Siggi had a passion for life that can only come from witnessing so much death,” Greene says. “He lived one of the most remarkable success stories of postwar America, and my privilege was helping make that story wider known.”