The film describes the departure of Amirani's family from Iran to England and then follows Amirani as he uncovers the evidence of the plot hatched by British and US intelligence, led by the CIA's Kermit Roosevelt Jr.[4] Central to the documentary is a series of clips in which actor Ralph Fiennes reads from a transcript of an interview with MI6 agent Norman Darbyshire, who admitted to plotting the coup (codenamed "Operation Ajax") together with the CIA.

The website's critics consensus reads: "Rife with the political intrigue promised by its title, Coup 53 is a spellbinding documentary with the heart of a thriller.

"[14] During the 2019 BFI London Film Festival where Coup 53 had its British and European Premiere Allan Hunter of Screen Daily called the film "as compelling as a John Le Carré novel or a Costa-Gavras classic" with "pulse-racing discoveries" and that director "Taghi Amirani's forensic focus and expert storytelling create a vital docu/drama with the potential to reach far beyond history buffs and conspiracy theorists".

"[21] Joe Morgenstern of The Wall Street Journal called Coup 53 "a formidable achievement" adding "As history lessons go, this is a powerful one in which a wealth of interviews and stunning graphics have been pulled together, with extraordinary attention to detail, into an intricate but lucid whole.

"[25] Larushka Ivan-Zadeh in The Times gave the film 5 stars and said "Ralph Fiennes appears, lending a wry le Carré air to proceedings as an enigmatic MI6 agent with an explosive testimony.

"[27] "It's like taking a swim in John le Carré's brain" said Dave Calhoun in his Time Out review titled "Shadowy spies and questing journalists abound in this taut, compelling doc".

Savlov went on to say "a spellbinding rabbit-hole of a movie, rife with outsized characters and conspiracies galore, but also and perhaps, more importantly, an eye-opening window onto the U.S. and Iran's current state of mutual enmity.

Granada TV producers publicly challenged a claim reported in The Observer on August 2, 2020, that an interview with Darbyshire had been filmed for End of Empire - Iran but subsequently removed from the programme under pressure from the UK government[37] In a letter to The Observer on August 16, producer Mark Anderson and researcher Alison Rooper stated that Darbyshire had refused to be filmed and that the interview transcript quoted in Coup 53 was an off the record research interview[38] Their letter pointed out that in 1985 an article published in The Observer the day before End of Empire - Iran was due to be broadcast on Channel 4 confirmed this.

[39] On August 18, more doubts emerged over Coup 53's censorship claims when Correspondent World suggested one of the film's key interviewees was now unsure about his testimony.

End of Empire - Iran producers claim that the "off-the record" audio-only research interview Alison Rooper conducted with Darbyshire was important to their work in which they clearly show MI6's role in the coup.

In November 2020, The Observer reported that Baroness Helena Kennedy had been asked to mediate between the Coup 53 filmmakers and the End of Empire program-makers, but the negotiations had broken down.

[52] Amirani and Murch told The Observer that they faced "a painful choice between a long legal battle or making expensive changes to important elements of their film" in order to regain the right to license footage from End of Empire - Iran.

In late November 2020 Matrix Chambers and the law firm Carter-Ruck acting on behalf of Amirani and Murch sent ITV Archive opinion letters showing that the threat of End of Empire's lawsuit had no legal merit.

[11][53] Without a studio or distributor backing, Coup 53 went on to qualify for the BAFTA in six categories including Outstanding Debut by a British Director, Best Documentary and Best Editing.

[55] They challenge the suggestions made by one of the interviewees (Hedayat Matine-Daftary) that they censored the key interview with MI6 agent Norman Darbyshire to downplay MI6's role in the coup.

The cut-up transcript is unique because it is the only original document with Darbyshire's name typed on it, including handwritten notes by the End of Empire production team.

[11] Website contributors also claim that the film gives insufficient credit for extensively using End of Empire – Iran footage and for its pioneering research uncovering British involvement in the coup.

End of Empire researcher Alison Rooper has stated in her 16 August 2020 letter to The Observer[59] that the transcript is an accurate record of the Darbyshire interview.

Later, Alison Rooper states that the transcript can be seen online at The National Security Archive website[60] On 17 August 2020, two days before the release Julian Borger of The Guardian wrote on article based on the release of the Darbyshire transcript by the producers of Coup 53 to The National Security Archive[61] Several contributors to Coup 53 have criticized the film and its use of their contributions.

Murch and Amirani point out that Trevelyan also filmed Sir Evelyn Shuckburgh for the Iran episode at the Savoy Hotel (Slates 19–21 on 15 February 1983).

"[64] In a post screening Q&A on 23 September 2022 at the Irish Film Institute Documentary Festival Taghi Amirani said that "the attacks by End of Empire on Coup 53 had not only made the film stronger but attracted the support of some of the most distinguished and respected filmmakers in the world including Michael Moore, Errol Morris, Chris Terrio, Paul Hirsch, Mike Leigh, Werner Herzog, Oliver Stone and David Puttnam.