Last year, the FBI arrested a pair of ISIS-inspired women in Queens, New York, with designs on constructing a bomb and detonating it somewhere within the contiguous United States. Undercover agents from the Bureau revealed that the women had professed interest in absorbing the “science” of bomb-making, and claimed that “we are living... the last war, the big war before the end of day starts, in English they call it Armageddon.” In order to familiarize themselves with the art of explosives, they downloaded copies of The Anarchist Cookbook.Since its 1971 publication, that tome, a how-to guide for bomb- and weapon-making as well as a call for violent insurrection—“respect must be earned by the spilling of blood,” it declares—has sold over 2 million copies and been linked to dozens of terrorist attacks both in the U.S. and abroad, including: the Croatian separatists who planted a bomb in Grand Central Terminal and hijacked TWA Flight 355 in 1976; a series of abortion clinic bombings in the 1980s; the Oklahoma City bombing in 1995; the Columbine High School massacre in 1999; the 7/7 London bombings; the 2011 Tucson shooting targeting U.S. Rep. Gabrielle Giffords; the Boston Marathon bombing; and the Aurora shooting in 2012 during The Dark Knight Rises.

The Anarchist Cookbook was written by William Powell in 1969. Then 19, the British-born and American-raised young man said he was “fed up with the government” over the Vietnam War, and subsequently spent four months pairing over-exaggerated revolutionary rhetoric with instructions for how to make DIY drugs, weapons, and bombs culled mainly from military manuals at the public library. Call it Anarchy for Dummies.

Powell is the subject of Charlie Siskel’s (Finding Vivian Maier) contentious new documentary American Anarchist. Premiering at the 2016 Venice Film Festival, the film consists of a week of rare sit-down interviews shot at Powell’s home in Massat, France, last summer, and examines the controversial author’s entire life—from his troubled upbringing to the penning of the book to the 40-plus years he spent after its publishing as an educator to special needs children, atoning for that one extraordinary stain.

“I expected to go there and find someone who was ready to bare his soul because he was ready to talk, and because I had indicated to him I was interested in the complexity in the story, and that he had made this youthful mistake and was ready to look back,” Siskel tells The Daily Beast.

That was not the case.

Powell is now 65—a bespectacled, professorial, mild-mannered old man, and a far cry from the bearded, Che Guevara look-alike he was at 19. He’s lived outside of the U.S. for the past 36 years of his life, running a series of schools abroad and later training centers for teachers of emotionally disturbed children, and even writing a book on the international schooling of at-risk youth funded by the U.S. Department of State. “The irony is not lost on me,” he says of his current profession.

In the beginning of the film, he’s reluctant to take responsibility for his book’s contents, claiming it “wasn’t a call to action,” that he wasn’t aware of its connection to acts of terrorism until the release of Michael Moore’s 2002 documentary Bowling for Columbine, and that he’d only received approximately $40,000 in royalties from its publication—though a newsletter unearthed by Siskel in the archives of Columbia University from its publisher, the late Lyle Stuart, revealed Powell had made upwards of $200,000 from it.

“That’s what we all do in our own lives: construct a narrative about our past that edits out some of the difficult stuff so we can sleep at night and live with ourselves,” says Siskel. “In his case, he’d created this Frankenstein’s monster that he’d lost control of, and it was easier to put it away in a box and spin it—to others, and to himself. But he was willing to let me confront him with those uncomfortable details about his past.”

Powell’s story is, like most, more than meets the eye. He grew up the son of the spokesman for the Secretary General of the UN, and after spending his early years in his native Great Britain—where he was bullied at school—moved back to the U.S. at 11. There, he was a troubled youth, enrolling in, and getting kicked out of, a series of boarding schools. Once, he pushed a teacher’s car into a ravine. Later on in the film, Powell reveals the potential motive behind his animus against authority: his sexual molestation as a teen at the hands of his headmaster.

In the late ’60s, Powell was a hippie living in Greenwich Village and working at a bookstore on the Lower East Side when he decided to pen The Anarchist Cookbook. He claims to have written the book in complete solitude, saying, “When I was alone with the typewriter, I was confident,” before adding in the very next breath, “No, I don’t think I was confident.” The manuscript was pitched to a number of publishers who all turned it down, but eventually accepted by an independent publisher named Lyle Stuart, who offered Powell a $2,000 advance yet retained the copyright.

“It was an early test case of these stories of young people who, the trolling and anonymity is one part of it, but this phenomenon—in Jon Ronson’s book, So You’ve Been Publicly Shamed—of young people who do something dumb, are not thinking, and put something on the internet and cannot take it back. Bill is a young, pre-internet version of that,” says Siskel.

But Powell, who claims to have never even attempted any of the recipes in his book, did benefit from the fact that his book was published before the internet, and could have taken any number of steps to attempt to either disown it or block its publication. This is where things get tricky.

In 2013, an 18-year-old student named Karl Pierson entered Arapahoe High School—just 8 miles from Columbine—armed with a pump-action 12-gauge shotgun, a machete, three Molotov cocktails, and 125 shotgun shells worn in bandoliers across his chest. He had schoolroom numbers scrawled on his arm, along with the Latin phrase Alea iacta est, translating to: “the die is cast.” The young man was on the hunt for the school’s debate coach, who’d recently demoted him on the team. When he couldn’t be found, Pierson randomly shot 17-year-old Claire Davis in the head—she died eight days later—and failed to ignite one of his Molotov cocktails, before turning the gun on himself. Friends of Pierson’s later revealed he’d been consuming The Anarchist Cookbook for years.

Later that year, Powell penned an op-ed for The Guardian—his first public mea culpa, save a brief author’s note he’d written as an addendum for Amazon.com in 2000. Calling its premise “profoundly flawed,” he wrote, “The Cookbook has been found in the possession of alienated and disturbed young people who have launched attacks against classmates and teachers. I suspect that the perpetrators of these attacks did not feel much of a sense of belonging, and the Cookbook may have added to their sense of isolation.” He later added that it should “quickly and quietly go out of print.”

Throughout American Anarchist, Siskel repeatedly questions Powell as to why it took him so long to disavow the book—leading to a heated confrontation with Powell and his wife, Ochan, in their kitchen. In the film, it’s revealed that he could have potentially put a stop to its publication decades ago, instead opting to receive a $10,000 buyout. Publishing rights to The Anarchist Cookbook have changed hands numerous times since, and are now controlled by Billy Blann, a kooky old man in El Dorado, Arkansas, who owns the tiny printing house Delta Press—and was once accused by local leaders of running a “satanic stronghold.”

It’s revealed in the film’s end credits that Powell passed away on July 11, 2016, of a sudden and unexpected heart attack. As Siskel was still in the process of editing the film, the author wasn’t able to see it before he died. This is, in a sense, his final confession.

“It fills me with remorse,” Powell says of his book late in the film, finally breaking down a bit. “I grossly underestimated the controversy it would provoke… I do feel responsible for the ways in which the book has been used.”