Helen Mirren tells Ian McKellen about that time she was friends with a con man

Helen Mirren and Ian McKellen star in “The Good Liar,” a film about a career con man named Roy, played by McKellen, who sets his sights on the recently widowed Betty, played by Mirren, in order to swindle her out of millions.

For McKellan, signing on was a no brainer. He’d worked with director Bill Condon before on “Gods and Monsters,” which earned him a best actor Oscar nomination in 1999. Condon won for best adapted screenplay for the movie. But having not yet read the script, McKellan had no idea he’d be playing a con man. Once told, he immediately conjured up an image.

“Because the film took place in London, there’s a myriad of extraordinary people and ordinary people there and we all fit in together, but I could easily imagine that [Roy was] the sort of person who will be able to navigate the problems of the being in that city,” McKellan told CNN, adding, “Not that I’d want to spend much time with Roy.”

So he found the character unlikeable? McKellan only laughed that he was relieved to “have gotten him out of my system.”

Mirren, who spoke with CNN alongside her costar, said that despite the evil intentions of McKellan’s character, she found him to be “utterly, utterly charming.” Which struck her as eerie, she explained, since she discovered not so long ago that she had actually been good friends with a real-life con man who’d been caught fleecing her circle of friends out of money.

“I have met a con man or two in my life, actually a major con man,” Mirren said, explaining that she found out only when he ended up behind bars. “He went to prison. For fraud. For financial fraud. And he was not far off [from Roy]. Unbelievably charming.”

While Mirren said she was was not financially cheated by him, she knew him “very well,” and was shocked to learn he was not, in fact, an accountant, like he’d claimed.

“He was a smaller Bernie Madoff, he knew what he was doing and people trusted him,” she said. Mirren said she pulled from the experience for the role, in order to better understand how someone like McKellan’s character can be both charming and a liar. She said the character is one of the most fulfilling roles she’s ever played.

“Women’s characters are often very underwritten. This one absolutely wasn’t,” she said. “It was like right up there alongside of the role that Ian plays.”

Mirren said she never once had to “adjust a scene,” change wording, or fight for her character, it was all taken care of by the director.

Like McKellan, he’s the reason that Mirren signed on to the project.

“If the people making the movie are of that kind of quality, you hardly, hardly need to read [the script] beforehand,” she says. “How fabulous to find a piece of work that has two absolute protagonists of equal stature within a wonderfully twisty, unexpected story.”

“The Good Liar” hits theaters Nov. 15.