LOS ANGELES: For his second film as director, British actor Ralph Fiennes lifts the cover on a little-known secret about classic English author Charles Dickens: his decade-long adulterous affair with a young actress.

Fiennes, a Shakespearean actor who made his debut behind the camera with 2011's “Coriolanus,” used a 1990 biography as the basis for “The Invisible Woman,” on limited release from Wednesday in the United States.

When Dickens fell in love with 18-year-old Ellen “Nelly” Ternan, the “Oliver Twist” author was 45.

He ended up separating from his wife, defying Victorian conventions, while his lover was condemned to a life of secrecy she found intolerable.

“People are surprised, they don't really know the story. In biographies, they have written about it, but no one wanted to focus on it,” Fiennes told AFP, saying that for this film, he had “not had much interest in” focusing on Dickens.

“Dickens was not the leading component, it was Nelly. What moved me to make it was how does this young woman, how does she find closure? How does she find a reconciliation with herself about this secret life with this man?

“I was moved by her. And then alongside her comes Dickens with all his fireworks and his energy and his charisma,” added Fiennes, who plays the writer in addition to directing.

To portray Nelly, he chose fellow Briton Felicity Jones. “I was looking for a really strong sense of interior life, because however you tell the story, I think Nelly is reactive,” he said.

“It was Dickens who pursued. I wanted her reaction to have its own quiet interior drama. Felicity has this great gift of suggesting all kinds of thoughts underneath the skin, behind the eyes, and that's what I wanted.

”Jones said she “found almost instinctively that Nelly was very contained, and that there was something quite mask-like about her and that she didn't give all her cards away.

“There was something very watchful about her. But I felt that inside and underneath she's incredibly passionate, and I rather liked that contradiction in her,” the actress said in an interview.

For his first film as director, Fiennes took on a Shakespeare tragedy he was familiar with from his thespian background. For his second movie outing, the material was less comfortable.

“I could remember 'Coriolanus' and the things I wanted to do better. But of course, a whole new set of problems comes out of the new situation,” said the 51-year-old actor.

"But because I had come through it and done it once, that gave me a kind of foundation of confidence."

Nominated for Oscars for his roles in "Schindler's List" (1993) and "The English Patient" (1996), Fiennes brought his acting sense to how he directed his fellow cast members on "The Invisible Woman."

"He's really focused on performance. Sometimes, directors sort of leave you to do what you want. But Ralph, with all of us, was very involved and would really push us," said Jones.

The actor-director's calm demeanour does not prevent him from pressing to get the best out of his performers.

"Obviously, because he's an actor, he can see phoniness a mile off," said Jones.

"I wouldn't say that I was scared, I admire his work and his honesty. There is a seriousness to Ralph that sometimes people find intimidating. But that seriousness comes from a real integrity in how he lives his life.

"And he expects that integrity from other people," she said.

Fiennes said he brought both his theater and film acting experience to the movie.

"People talk about people doing less on film. Yes, that's the sort of guiding rule," he said.

"But sometimes, we've all seen some great performances where something explodes from someone and it's big but actually, it's so real. And people do explode in life, people go crazy."

"The Invisible Woman" comes out in Britain and Ireland in February, and in the Netherlands in March.