One can reasonably argue that every modern Middle East foreign policy failure is a direct consequence of the 1953 coup d’état of Iranian Prime Minister Mohammad Mossadegh. In other words, the creation of the modern Islamic State, which came to power in the aftermath of the 1979 Iranian Revolution, was fallout of the West’s own creation from two decades earlier: a joint British/U.S. operation that replaced Iran’s democratically elected leader with the Shah because of a matter as petty as oil profits.

That it occurred isn’t much of a revelation, despite the United Kingdom never admitting guilt and the CIA only confessing its involvement in 2013, but Taghi Amirani’s Coup 53 nevertheless attempts to fill in a number of historical blanks to prove its worth. The documentary compiles a giant elaborate puzzle from over a decade of evidence gathering and interviews that feels thrilling and haunting once assembled.

Presented as a collaboration between Amirani and film editor Walter Murch, perhaps best known for his work on Francis Ford Coppola’s most acclaimed early films, Coup 53’s main focus is uncovering the testimony of an MI6 agent named Norman Darbyshire. Darbyshire presumably oversaw the planning of the coup, Operation Ajax, from the British side, and the film’s front half follows Amirani as he learns from Iranian and British sources how far down the rabbit hole this man’s involvement went.

The evidence ranges from boxed documents to long concealed film footage, but the smoking gun, per se, is an unredacted transcript of an interview with Darbyshire for the British documentary series End of Empire, which was mysteriously leaked to the Observer. It’s a blunt and cynical confession that, for mysterious bureaucratic reasons, never saw the light of day.

Murch’s editing helps turn this movie into an extended “this is how it happened” exposé, with footage from generations of archival material. Statements from aging allies of Mossadegh (some of whom have since died), footage of CIA and MI6 agents, and even an interview with Ardeshir Zahedi—the Shah’s foreign minister and son of the Iranian general at the center of the coup—are cobbled together into a giant web detailing the political conflict’s origins, boiling point, and fallout.

As for the enigmatic Darbyshire, Amirani brings him to life with cinematic flair by having Ralph Fiennes re-create Darbyshire’s original interview, delivering the transcript statements with a stern, matter-of-fact performance, not unlike his recent tenure as James Bond’s M. I can’t help but feel that, had this been a Hollywood drama, Fiennes would probably have been cast as the same character.

Admittedly, both halves of Coup 53 work better separately than how they transition into one another. Once Fiennes’s scenes and the interviewees start breaking down the coup, everything involving Amirani’s interactions with journalists and archivists is dropped and never revisited. It’s not entirely distracting, as watching all the puzzle pieces connect together is still very riveting. While Amirani probably didn’t want to nudge the viewer in any direction, I still expected some kind of response from the filmmakers investigating this dark truth. Instead, it feels like the truth overtook their involvement near the end.

Then again, Amirani already knows his country’s history to be rightfully outraged over what Iran lost. American viewers like myself, on the other hand, are forced to comprehend a violent event regularly ignored by U.S. history that feels unnecessary in hindsight and during the era it happened. Mohammad Mossadegh is presented as the kind of intellectual, moral leader who should have theoretically been a great post-war ally for the West. Yet the British so wanted Iranian oil and, viewing Mossadegh’s nationalization of the Anglo-Persian Oil Company as a middle finger to their colonial beliefs, used Eisenhower-era anti-Communist fears to garner America’s aid in defiance of an international court decision.

Their coup tactics feel like a precursor to modern disinformation campaigns: buying out newspapers to print slander, creating mob chaos among protests, and even reframing failed coup attempts to make Mossadegh look like the agitator. That its success only emboldened future U.S. “interventions” without fear of consequences reveals how modern anti-democratic battlegrounds were unwittingly created around the world.

Coup 53 feels part investigative thriller and part straightforward documentary, semi-stitched together a little jarringly in the middle. But it retains a disturbing core message: pinpointing the exact moment that ruined any future of Iranian democracy by First World powers claiming to uphold it. It’s the kind of story that, as Fiennes/Darbyshire states bluntly, “you won’t find in any book” because the truth’s decade-long ramifications are too great, and too embarrassing for either party to admit.