Looming large: Lawrence Wright on The Looming Tower

Wrenn Schmidt (Diane Marsh) and Tahar Rahim (Ali Soufan) in Looming Tower.

Lawrence Wright wrote The Looming Tower, which spawned a TV show. He talks to Jane Mulkerrins.

"I knew that writing The Looming Tower was probably the most important thing that I would ever do with my professional life," says Lawrence Wright.

That is no small claim, considering that 70-year-old Wright, a long-time staff writer at The New Yorker, is also the man behind the explosive book Going Clear: Scientology, Hollywood, and the Prison of Belief, which formed the basis for a hugely successful 2015 documentary on the controversial Church of Scientology.

But it does explain why it took a decade to get The Looming Tower to screen. The bestseller involved five years of research and more than 600 interviews with members of the intelligence services and counterterrorist experts. "It felt like a mission, but it was also a hell of a story, and I knew that I had something very important to say. I didn't know, for a long time, why I was so resistant to [adapting] it," Wright admits. "But I knew I wanted it to be right."

Now, 10 years after the book won him the Pulitzer Prize, Wright's dense, detailed, definitive tome on the road to 9/11 has finally been adapted for television.

He has, once again, teamed up with Alex Gibney, director of Going Clear, to produce the 10-part miniseries starring Jeff Daniels, Peter Sarsgaard, Tahar Rahim and Michael Stuhlbarg, which highlights the rivalry between the CIA and the FBI, and the subsequent inaction, which failed to prevent the deadly terrorist attacks on 9/11. "They are at war with each other," says Texas-born Wright, when we meet in Los Angeles ahead of the show's US premiere. "The CIA has an obligation to collect intelligence, and they are jealous of that information; the FBI has an obligation to take that intelligence, use it to trace criminals, arrest them and put them on trial."

"There is nothing that the CIA hates more than having all this intelligence be produced in a trial," he continues. "The antagonisms that spill out from those two different missions will never really go away."

The CIA, he reports, was reluctant to help with his research for The Looming Tower, and was unco-operative in the production of the series too. "I always believe that it is a mistake not to get your perspective across if you believe in it. Then you have the opportunity to tell your story," he reasons. With Zero Dark Thirty, the Oscar-nominated 2012 film about the intelligence operative who found Bin Laden, the CIA was apparently only too keen to co-operate. "In fact, they were sort of instigating the project, because they wanted to get their version out," he says. "But The Looming Tower was a problem for them; even though it became required reading in the agency, it shows that the CIA, like all of our government agencies, has flaws, and there were failures that were very consequential. And no one has been held accountable."

Though the series, like the book, is non-fiction, it is peopled with dramatis personae few fictitious dramas could dream of, including, most notably, the two men at the centre of the FBI's investigations: Ali Soufan, a young Lebanese-born operative, and John O'Neill, his boss.

Soufan, who was only in his mid-20s when he began investigating major terrorist attacks, including the bombing of the USS Cole, is, says Wright, "a Muslim-American hero, a true patriot. We [the US] are really fortunate that we had someone with his intelligence and integrity." Soufan - who went on to work for Rudy Giuliani when he was mayor of New York, has also served as a consultant for the series - working closely with the writers, and with Rahim, the actor who plays him. O'Neill, meanwhile, is a larger-than-life character, an exacting, demanding boss, who also kept multiple mistresses, and who, tragically, was killed in the attacks on 9/11. His story was one of the most compelling elements of the entire narrative for Wright.

Jeff Daniels, left, and Tahar Rahim in a scene from "The Looming Tower.".

"When I spotted an obituary for John O'Neill, a few days after 9/11, it made him sound like he was a disaster - that he was washed up at the bureau, and had taken a job running security at the World Trade Centre. And I thought, how ironic, that the man who was supposed to get Bin Laden didn't get him; Bin Laden got him instead. That felt Greek to me."

But O'Neill, Wright also reports, "gulped life; everything was intense".

"I met three women who all thought they were engaged to him," he laughs. "He had a wife and two children in New Jersey too, and they all met at his funeral." The author does not believe, however, that it was ever his place to judge.

"I didn't care if he was a hero or a mess. He was a brave man, and the challenge was to present all those sides of him, and let the reader - and now the viewer - decide."

Lowdown

The Looming Tower, March 15, 8.30pm on SoHo
The Looming Tower, March 15, 8.30pm on SoHo