Since graduating from RADA three years ago, Morgan Watkins hasn’t exactly opted for light relief when it comes to the plays he has performed in. From Deborah Warner’s production of Mother Courage and Her Children at the National in 2009, to Sean Holmes’s revival of Saved at the Lyric Hammersmith last October, tragic themes have become his daily bread. As he returns to the Lyric to play Eben Cabot in Desire under the Elms – arguably his most challenging theatrical role to date – the themes of Eugene O’Neill’s classic play are no less morose. Like Saved, it even features its share of infanticide.

So what is it about the theatrical dark that keeps drawing the young actor in? “I don’t think it’s particularly a preference I have,” Watkins explains. “It’s just something I seem to end up doing – maybe because I’m not afraid of it. But I do like plays and films that explore the darker issues in life: the more perverse and stranger things. What O’Neill’s done in the play is he’s given these quite simple people in rural America in 1850 this incredibly tragic set of circumstances and let it burn. It’s not a play about society as such, it’s a play about the human psyche. I thought it was fantastic, an amazing piece of writing, and Eben was a fascinating character to explore. He’s got a really volatile way of thinking about things and he can literally flip in a space of five seconds from one opinion to the opposite. He is definitely a very troubled, trapped man.”

In O’Neill’s play, which resituates Greek tragedy in the rural New England of the late nineteenth century, Eben is the youngest son of Ephraim Cabot, a brutal and exacting man who has for years repressed his family. “Eben was 15 when his mother died,” Watkins tells me. “After she died, he had to take over the mother’s role in the house and he began to realise what she’d been through. Eben is a thinker, a sensitive soul. He couldn’t believe the way in which they’d all stood by and let his father slave her to death. So he takes it upon himself to avenge his mother’s death in some way – and he’s kind of working that out as the play starts.” It’s at this point that Eben’s elderly father [Finbar Lynch] suddenly arrives home with a new wife and, as Watkins juicily puts it, “everything goes tits up”.

“It’s a complete shock because he’s 75-years-old: it’s the last thing that they expected”. Less expected still, however, is the adulterous relationship which develops between Eben and his father’s bride, Abbie [Denise Gough]. “I think at first there’s a huge mutual attraction between them: she’s physically very attractive to him, and vice versa. And Eben hasn’t got much experience of women: even though he’s 25, he’s quite a repressed character. He can’t just go to a nightclub and see loads of girls in the way that I might be able to today. But I do think Abbie is the driving force at first.”

Strongly attracted to Eben, Abbie tries to seduce her stepson, but is initially refused. He resists Abbie “because she is counter-intuitive to what he wants to achieve, which is to regain his mother’s farm and put his mother’s spirit to rest.” However, Eben’s reluctance is short-lived. “Later in the play you see that change, and they completely connect at one point.”

Creating a convincing onstage relationship was an intense but oddly uncomplicated process for Watkins and his co-star Denise Gough. “Everyone who has watched the runs has said how believable it is – how believable the feelings are between us. But it’s just that we’ve been committing to the scenes and discussing and working on them. We haven’t done any exercises to get close to each other or anything. I think we’re both quite honest actors, me and Denise. And I think when you both just play the scenes and believe in the scenes and the situation, it just happens.”

But with such extremes on stage – adultery, infanticide and these overpowering echoes of Greek tragedy – how do the performers manage to preserve the realism? “It’s actually quite tough because the themes are so huge. Everything is so dramatic, there’s so much emotion and the stakes are so high. You’ve just got to tell the story at the same time and in fact, in life, in the most tragic circumstances, we don’t always behave epically. There’s a lot of logic and problem-solving as opposed to just dwelling on problems. So I personally try to pick it apart and play the scenes for what they are. Even if the stakes are really high and there’s something really dramatic going on, you’ve got to play it with accuracy and not overdo it. That’s the key. It’s just imagination and commitment, acting, and I think if you put yourself in that situation and believe what is happening then it organically will be what it should be.”

This straightforward commitment to the text is also characteristic of Sean Holmes’s style as a director, and is why Watkins so enjoys working with him. “He’s just very simple, Sean, he’s straight to the point. Some people in theatre and in acting think that we’re doing some sort of sacred, epic thing. And in some ways when it’s great it is kind of like that. But Sean is not the type of guy to think that at all – he just gets in the room and gets on with it. He treats everyone with equal respect, as if you’re just normal. That’s what I find very appealing about working with him, and I find it easy to listen to and respect everything he says. He just picks the play apart: we have a read and we start attacking the text and discussing it.”

With an appreciation for this fairly no-nonsense approach to the job, perhaps it’s no wonder that Watkins is gradually making his mark on the silver and small screen as well as the stage. As he treads the boards at the Lyric, his face will also be appearing on TVs across the country as a regular on the second series of the BBC’s iconic drama, The Hour. So as he becomes more of a household name, I asked him whether he still plans to keep his feet firmly on the stage: “I’m up for doing as much as I can of anything,” he says, “as long as it’s good writing and a good character and good drama for people to watch and enjoy. I do love theatre: I love rehearsing every day, the sort of hands-on side to theatre and the fact that it’s constant. But I also love the medium of film and television – it’s wonderful in its own right. I just want to do great drama really, wherever that is: as long as it’s bloody good.”

Desire under the Elms previews at the Lyric Hammersmith on Wednesday 3 October and plays until Saturday 10 November 2012. For tickets and more information, visit www.lyric.co.uk.

Image credit: Morgan Watkins as Eben Cabot and Denise Gough as Abbie Putnam by Keith Pattison