Journalists generally understand that extracting the truth from a career spook is a tricky business. What’s striking about the Oscar-nominated doc The Gatekeepers (opening Friday [March 1])—in which six former heads of Israel’s fearsome internal security agency, Shin Bet, divulge their experiences—is how fantastically sincere they all appear to be. Especially when every one of them laments Israel’s brutal tactics in the occupied territories, decries the rise of the right wing, and calls for a two-state solution to the “Palestinian question”.

Calling from Los Angeles, director Dror Moreh tells the Straight that he believed “about 99 percent” of what he was told by these professionally shadowy figures. “The thing for me is to try to understand if they had another interest in speaking,” he says. “Especially on those really morally questionable issues that we dealt with: the targeted assassinations, the torture, the right to give the order to kill without a trial. On those issues, I can say, first of all, they have to defend the decisions that they took, but I didn’t feel that they tried to whitewash what they did.”

The viewer is left with the same impression, more or less. Watching Avi Dichter (Shin Bet’s director from 2000 to 2005) equivocate over the morality of dropping a one-tonne bomb on the home of Hamas leader Salah Shehade forces the viewer into a kind of cognitive dissonance, especially when Moreh illustrates the event with the image of one of the eight children who were killed in the attack.

“I have to tell you that if you think the work of the Shin Bet is giving aid to starving people around the world, you are mistaken,” Moreh states. “These guys, this is what they do. What do you think the people that work in the CIA are made of? This is what they chose as their career, and it’s not vegetarian work, believe me. They fight terror. They fight terror in ways that are questionable and morally wrong, and this is what you saw in what happened in the 300 line.”

The 1984 “300 line” incident (or the “Bus 300 affair”, as it was also known)—in which two of four Palestinians who hijacked a bus were apprehended and brutally executed—was a turning point for Israel, for Shin Bet, and for its director at the time, Avraham Shalom, who remains the most notorious of the six men Moreh got on camera. A wild-eyed photo of Shalom from the ’80s speaks volumes, and yet it’s Shalom—who was alleged to have given the execution order and ordered a cover-up, and who was later pardoned—who argues most passionately for a diplomatic solution, even as he states: “In the war against terror, you forget about morality.”

“Look, for me, this guy, he’s a legend, especially because of the 300 line. I never spoke to him before; I never met him, and for me to sit in front of someone like that…” Moreh trails off. He describes Shalom as “the most difficult interview I did in my life, ever”, but he prodded the former director about the 300 line anyway. Shalom’s response might provide five of the most electrifying minutes of cinema you’ll see all year. “And then you see this old grandpa with the suspenders sitting in the chair and waiting for the next question to come, silently,” Moreh continues.

So how does the filmmaker reconcile the bully feared by Shalom’s colleagues with the thoughtful senior on-screen?

“Thirty years,” Moreh replies with a chuckle. “Thirty years outside from being head of Shin Bet.”