Having starred in films like Jack Reacher and Lee Daniels’ The Butler, UK-born David Oyelowo talks to Elbert Wyche about his lead role in Nightingale, which premiered at the LA Film Festival in June.

Elliott Lester directed from Frederick Mensch’s Black List screenplay about a man called Peter Snowden and his obsession with an old Army friend named Edward. The film follows Peter as he records his private thoughts and feelings – his nightingale song – in the days leading up to his planned reunion with Edward. WME Global handles US rights.

Oyelowo discusses his first immersion in method acting to properly represent mental illness on film and talks about why he had to temporarily move away from his family during production. He stars later this year as Martin Luther King Jr in Selma and will also be seen in Christopher Nolan’s Interstellar and JC Chandor’s A Most Violent Year.

How did the script for Nightingale make its way to you?

It was a very orthodox way. It came through my agent. I realised very quickly that it was a very unique piece. I was aware that a few other high-profile actors had toyed with the idea of doing it and for whatever reason it didn’t work for them. When it came to me it became evident that this was a do-or-die situation. It was a big risk to take because it was 98 pages of dialogue for one actor. I had to ask if it could be done when I first read it. It had a very visceral impact on me, partly because of my stage work. It just felt like it was a beautiful marriage of what you’re demanded to do on stage as an actor and the possibilities that can open up cinematically.

How did you research the role?

Anyone that sees the film will be able to tell very quickly that Peter Snowden, the character that I play, is a very disturbed individual. He is mentally unbalanced, so to speak. So I spent a lot of time talking to a psychiatrist about the specifics of Peter’s condition. I guess the old way of speaking about it would be multiple personality disorder. He’s a guy who is very fragmented. He has dealt with a lot of trauma in his life. The way he deals with it is to embody different aspects of his personality to deal with situations that arise. This is a very real condition that plagues a lot of people all over the world. For me, I didn’t want to just portray a clichéd version of that so a lot of my time was spent talking to the psychiatrist.

Was it difficult playing to the camera and how is that different from playing to another actor?

It was initially quite difficult. Even the phone calls that we have in the film, a lot of them to my sister, some to my mother’s friend and to an individual that Peter is obsessed with, as well as [the individual’s] wife – there’s no-one on the other end of the line as we shot those. That was a very deliberate choice of ours because there’s also the question in Peter of, ‘Is he actually talking to someone or is he talking to someone of his own making?’ We largely wanted that to remain an open question. But I was constantly reacting, whether to a real voice or a voice inside my own head. It presented the added task of not only knowing what my character was doing in any given moment but also knowing what I was reacting to. In a normal film you actually have another actor to have that other end of the conversation [with], whereas as I had to conjure up both.

When you left the set everyday was being in the mind of that character hard to turn it off?

This was not an easy switch to turn off. Actually, it was the first time that I made the decision to stay in character for the duration of the shoot. I moved out of my house. I moved away from my wife and kids because I felt that I didn’t want this fairly disturbed individual to be around them for the three weeks that we were shooting. I moved into a friend’s apartment while they were away shooting something else. On set and away, I was largely this guy. He was so in his own head, his internal dialogue is so constant, I felt that if I switched that off I would either start to judge the character or I would lose a thread on that inner conversation. It was the first time that I made that choice.

It seems like a lot of pressure knowing that the film ultimately rests on your shoulders. Did you feel that?

The only pressure I tend to feel as an actor is the pressure that I place on myself to be as good as I can be in anything I choose to do. And I think if you feel like you can’t give a role or a film or a project your very best, you shouldn’t do it. So in having made the choice to do it the pressure really was for me to do as much work as I could to serve the character. If what you’re asking is did I feel pressure in terms of an audience, I don’t really take that on because no one is a bigger critic of my work than me. As long as I’ve done my work and as long as I can walk away from a situation knowing I’ve given it my best I’m able to sleep well at night.

What was it like working with Elliott Lester?

I had an amazing time with him. He has all those qualities you want in a director. He was very open, very collaborative. But also he had a very specific vision of what he wanted. Nothing beats being able to trust your director, especially with a piece like this where it can go several different ways. I can’t think of a single film that is quite like this film. When you’re doing a unique film like this you really want the captain of the ship to have a clear vision and he had that. We discussed so much before we shot it. He gave me films to watch, documentaries to watch, books to read. I could tell he really entrenched himself in the world of the film, which gave me a lot of confidence to dig deep as well. Visually, along with the director of photography Pieter Vermeer, to make one house feel interesting, fresh and new with each scene was very much one of his big tasks as a director that he rose to fantastically.

What’s next for you?

I’m in Atlanta right now shooting a film called Selma in which I play Martin Luther King Jr. That film is about King and his cohorts fighting to gain voting rights for black people in the South in 1965. It’s about that really dramatic fight between the Civil Rights movement and the governing bodies of the South, including Lyndon Johnson in 1965.