In 1973, Claude Lanzmann began work on a documentary about the murder of European Jews during WWII. Twelve years and more than 200 hours of footage later, he completed Shoah, a masterpiece widely considered to be the most important Holocaust film ever made.

Exploring the French iconoclast’s arduous path to creating his nine-hour-plus masterpiece, CLAUDE LANZMANN: SPECTRES OF THE SHOAH debuts MONDAY, MAY 2, exclusively on HBO. Academy Award-nominated in the category of Best Documentary Short Subject this year, the film includes previously unseen outtakes and features the 90-year-old filmmaker’s modern-day reflections on key moments in his life, as well as his hopes for the future.

Written and directed by Adam Benzine, the first major documentary on the filmmaker recounts his journey from the bright-eyed journalist of 1973 to the world-weary auteur of 1985. This poignant film features intense conversations in which he speaks candidly about his life experiences, focusing on the making of his magnum opus, an ordeal that changed him forever.

Featuring never-before-seen, digitally remastered archival footage, provided by the United States Holocaust Memorial Museum and Israel’s Yad Vashem, CLAUDE LANZMANN: SPECTRES OF THE SHOAH shines a light on both the challenges inherent in the artistic process, and the trials and traumas posed by one of the darkest periods of mankind’s history.

Following his 1973 directorial debut, “Israel, Why,” Lanzmann was contacted by Alouph Hareven, the director-general of Israel’s Ministry of Foreign Affairs, who commissioned him to make “a film that was the Shoah…seen through Jewish eyes.” Today, he reflects that it was “a decision that meant I would have to give up everything.”

Lanzmann’s insistence on not using archival footage meant he found himself traveling to 14 countries and working as a detective to procure interviews. He recalls visiting hair salons across New York in search of Treblinka survivor Abraham Bomba, a Jewish Sonderkommando who was forced to cut the hair of women sent to the gas chambers. When they finally came face to face, Lanzmann filmed their interview in a barbershop. Though initially impassive, Bomba became emotional upon recalling the story of a fellow barber and friend whose wife and sister entered the “showers,” a painful memory that Lanzmann urged Bomba to share by stressing, “We have to do it.”

Facing the challenge of how to get the Holocaust’s perpetrators on film, Lanzmann armed himself with a hidden camera and created a fake organization, for which he claimed to be writing a thesis on the triumphs of German forces. He vowed “to stay cold” in interviews, but the risks could have been deadly.

When Lanzmann and his assistant, Corinna Coulmas, traveled to Germany to speak with former SS officer Heinz Schubert, their plan to transmit footage to a minibus outside was compromised by the growing suspicions of Schubert’s wife. After four men burst in demanding they open their hidden camera bag, the two were assaulted while trying to escape. Hospitalized for a month, Lanzmann was charged with “unlawful use of the German airwaves,” though the charges were eventually dropped.

In 1980, Lanzmann began the five-year process of editing his massive amount of footage. Having promised a two-hour film in two years, “I had to lie to everybody,” he admits. Lanzmann became so overwhelmed during the process that he swam out too far during a beach trip in Jerusalem and nearly drowned, which he now believes was an attempt to commit suicide. He describes the day he finally finished work on “Shoah” as feeling like “a bereavement.”

Lanzmann also touches on his teenage years as a French Resistance fighter and his friendships with Jean-Paul Sartre and Simone de Beauvoir, the latter his “best friend” and onetime love interest, who “never let [him] lose hope” while making “Shoah.”

Eventually released in 1985, “Shoah” was met with critical acclaim, and Lanzmann was honored with numerous awards. Despite its success, he took a long time to recover. “We lived in a very difficult time,” Lanzmann says. “But at least it was an epic time and there was greatness in this.”

CLAUDE LANZMANN: SPECTRES OF THE SHOAH was written, produced and directed by Adam Benzine; co-producer, Kimberley Warner; editor, Tiffany Beaudin; original music by Joel Goodman; executive producer, Nick Fraser.