In the shadow of Alfred Hitchcock
Playing a real-life character was hardly a new challenge for Dame Helen Mirren - after all, she has previously portrayed three Queens of England, not to mention Tolstoy's wife, Sofya.
But unlike those, her latest true-to-life role, as Alma Reville, will be unfamiliar to most cinema-goers.
Reville was the wife of Alfred Hitchcock - she was was married to the acclaimed film director for over 50 years, until his death in April 1980.
And it is the story of their relationship, and Reville's role in bringing classic thriller Psycho to the big screen, that is brought to life in director Sacha Gervasi's first feature film, Hitchcock.
"With Alma, I had the advantage that nobody knew (her)," says Dame Helen.
"Everyone knows what Alfred Hitchcock looks like and sounds like, nobody knew what Alma looked like and sounded like and it's extraordinary that there's very, very little film of her. She very much kept in the background."
Reville entered the film industry before her husband, getting her first job at the age of 15 as a rewind girl in the cutting room at Twickenham Film Studios.
At 16, after moving to the London Film Company, she began training to be an editor and went on to work on many of her husband's films, both as editor and script writer.
The saying goes that behind every man there's a good woman and Dame Helen believes that Reville was happy to take a back seat.
"I think she was proud of the success of that partnership, as manifested by Hitchcock," she says, adding that Reville was equally proud of "the Hitchcock brand".
"She was as much a creator of that brand as he was," she explains.
"She was very happy, like the CEO of any big company, to stand in the background. Alma didn't want to be a public face.
"Film is an incredibly collaborative medium. The majority of the people who create a film have no public face at all - so film people are kind of used to it."
Director Gervasi agrees: "Hitch wouldn't have been Hitch without Alma. For every creative genius, there's someone lurking in the shadows who's not seeking the limelight, who is there to help and listen to all their craziness. That's a story I want to tell."
Despite Hitchcock's well-known infatuation for his leading ladies, Mirren believes Hitchcock and Reville had a solid marriage.
"They had a very happy and very successful relationship. There was never, ever a moment when there was a feeling that was breaking down."
Gervasi says he was fascinated by how Reville handled Hitchcock's obsessions.
"What must it have been like living with Alfred Hitchcock after he obsessed over these blonde goddesses? Eternally out of reach but who you could fashion and mould into this fantasy image."
The project gave Dame Helen the opportunity to work with Sir Anthony Hopkins for the first time.
"It was wonderful partly because we come from a very similar tradition, we both come from British theatre and we're not 'American actors', for want of a better word… We're very much of the school of 'get on there and do it.'"
The pair have both won Academy Awards before - Dame Helen nabbed a best actress Oscar in 2007 for The Queen, while Sir Anthony won best actor for his portrayal of Hannibal Lecter in Silence of the Lambs in 1992.
And this weekend, Dame Helen is up for a Bafta (her fifth nomination to date) for her portrayal of Reville.
The actress acknowledges that award recognition is crucial.
"Awards are important for a movie, especially for a small, low-budget movie like this one, although it doesn't look it. These kind of movies don't have huge marketing budgets, so awards are very important because they draw attention. We make movies because we want people to see them."
Gervasi hopes that, by bringing Reville to the foreground, the film will reveal the man behind the Hitchcock caricature.
"I think it (his marriage) makes him even more fascinating than he already is. It makes him richer and more human.
"He wasn't just some cinematic deity on a pedestal, he was a massively complex man... I think the films were, in a strange way, his therapy," he adds.
"Was he a monster, was he a god? He was all of those things but he was also a man who was an artist trying to work his stuff out through these movies."
Hitchcock is released in the UK on 8 February.