Playing the part of Alma, the wife of the legendary film director, Mirren is doing her part to bring to the fore one of Hollywood's untold love stories.
The woman and the creative soulmate behind the genius of Hitchcock, Alma Reville, is being brought to life in a new film starring Mirren.
Reville lived in the very large shadow cast - creatively as well as physically - by her very famous husband until now.More stories from Today Tonight
"I don't want to take anything away from the 'auteurness' of Hitchcock's work because he was an extraordinary inventive and iconic film director, but the only person he would listen to was Alma," Mirren said.
After almost a century as two of film and theatre's biggest British heavyweights, the dame and the sir, Mirren and Sir Anthony Hopkins have finally paired up in one of the most exciting films of the year.
And the Dame has revealed she had a touch of nerves ahead of filming.
Mirren said it was "a little intimidating. Sir Anthony Hopkins is a great, great actor, so it's always a bit nerve-wracking and intimidating. But not because he is intimidating - he's absolutely not, he's very welcoming and generous.
"It had been of a dream of mine to work with him. I'd always felt we were kind of a good fit along the line. And it's so fantastic to have that opportunity."
The film Hitchcock sees the famous director at 60, and desperate for a hit. With his devoted wife by his side they stumble on the story of serial killer Ed Geines and thus begins the backstory to the film that went on to shock the world: Psycho.
"I don't think either of them were into that sensual side of life - food and drink, and as we all know the dream of the perfect blonde woman, but the whole point was that she should be untouchable," Mirren explained.
'Untouchable' is a term one could easily ascribe to Dame Helen Mirren, who at the age of 70 remains in a class of her own - much like the man they called Hitch.
"I think Hitchcock was very British. And indeed Alma was. And they kept their Britishness intact in America. They loved America, they loved the opportunity they were given in the film industry and they loved living there. But they absolutely maintained their Britishness, they recreated their British house in Los Angeles, an English garden which you see a little bit in the film," Mirren said.
"I think a lot of the misunderstanding about Hitchcock was misunderstanding his Britishness. And also coming from the generation he came from - the economic background he came from. All of those elements just saw him as a weirdo."
Alfred Hitchcock never won an Academy Award for directing. However one of his films was names 'Best Picture' - surprisingly it was the 1940 film Rebecca.