When Mark O'Rowe began work on his new play Terminus, set in a shadowy Dublin, he found himself writing in epic verse and just went with the flow, he tells Peter Crawley

What kind of person writes an epic poem these days? Once a clear form of narrative verse, surging with majestic themes across a roiling sea of heroic quests, weathering divine interventions and twists of fate along the way, an epic is now generally free of poetry and refers either to a three-hour film, or a trilogy of them.

In his daring new work - possibly his most shocking and certainly his most comic - Dublin playwright Mark O'Rowe has written a thrillingly enjoyable epic. Terminus, his first play since the bleak horrors of Crestfall, four years ago, is a meticulously crafted piece which, it will surprise nobody to learn, is a monologue play. It may surprise quite a few people, however, to learn that O'Rowe has written it entirely in verse.

Here, for example, is one character describing a fateful escapade, that begins in her local boozer and which will lead us first to a Dublin construction site and from there into uncharted territories of the imagination: "We go, see the slo-mo ebb-and-flow of pub-spill; the mill, the babble, the rabble of wobbling waywards, exiled and aimless, unlike us as, purposeful and double-file, like kids on a dare, we head who the f**k knows where?"

O'Rowe, who makes his directorial debut with Terminus, considers it free verse, and although you can measure out whole sections in iambs, he is not someone you want to mess with. A warm and friendly presence, he makes for a fluid, engaging speaker with a smile that comes easily. But, given that his theatre has vividly mapped out a septic and violent underworld, a cautious person might notice, for instance, a small fresh dent at the top of his crown, or a large chip missing from the left lens of his glasses, and decide to tread with caution.

How did he come to write an epic poem? "I think it kind of happened by mistake," O'Rowe says, sitting in the Abbey bar on a sunny afternoon, skipping lunch before his first tech run in the Peacock. "I wrote a couple of lines and it had a certain kind of rhythm and a rhyme. I said, okay, I'll follow it."

Terminusbegan as a personal project, while O'Rowe struggled with a commission to adapt Joseph O'Connor's novel Star of The Seafor a big-budget Working Title film. "A lot of people have to read a screenplay," he says. "You have to wait for them to get back to you. You have a very short time to produce a new draft. I'm on my fifth draft of Star of the Seanow. It's going to go beyond 10. It's that kind of a project."

Terminus, although ferociously entertaining, is too fastidious in its construction to look like light relief. "I'd kind of spend most of my time on [ the screen play], but for an hour every morning I'd do my little thing for myself. And then of course I ended up with this epic f**king story that I had to write in a sort of free rhyme."

The interweaving tale of three characters best described as a vigilante Samaritan (Andrea Irvine), a lonely young woman who has cheated death (Eileen Walsh), and an unpleasantly engaging serial killer who has been cheated by death (Aidan Kelly), Terminusalso counts demons, devils and fantastical flights across the construction-crane-dotted skyline of Dublin among its elements. At times it reminds you of the frantic verse of Poe's The Ravenor the epic sweep of Milton's Paradise Lost.

"I've read Paradise Lost," O'Rowe begins. "No. Tried to read Paradise Lost, but never got past Book II." That he writes so exhilaratingly and humorously about dark phantasmagoria, however, seems to make them kindred spirits. (Milton, too, set out to write a drama, but ultimately let the language lead him into verse.) As William Blake put it: "The reason Milton wrote in fetters when he wrote of Angels and God, and at liberty when of Devils and Hell, is because he was a true Poet, and of the Devil's party without knowing it." I wonder if the same is true of O'Rowe, who writes lyrical evocations of brutality and degradation.

"I've never really spoken about this before," he ventures, "but, for every writer of my generation, their first inspiration has been Mamet and Pinter. They're the usual suspects. I think it's because they were the first writers to bring dialogue down to something very spare and quite naturalistic but with a lovely formality to it as well."

It was Mamet who inspired O'Rowe to write dialogue. "Ever since that," he says, "the thing that inspires me first is the language. I suppose that ties into the idea of poets, where it's really all about language." As for the Devil's party . . . "I didn't have a dark childhood," he says of his upbringing in Tallaght. "I had a very normal working-class childhood. But I enjoyed dark stuff, in terms of the books I read when I was young. Still do. Somebody said to me that if you just free associate, if you just sit down to write and free associate, one of the first things that will come out of your head is sex.

"Maybe it's tied into that in some way, because sex and violence are tied together very closely. Maybe it's something repressed within me that's coming out." He laughs shyly. "But the dark stuff's kind of fun, isn't it?" he continues. "I never felt I wanted to explore it or give reasons for it."

Since he is the gritty urban voice of a new Ireland, however, people are inclined to look for deeper social significance within O'Rowe's grimy displays. It's not something expected of Quentin Tarantino, I suggest.

"Yeah," he says. "If Quentin Tarantino has two guys rob a jewellery store, [ no one says] it's a commentary on poverty and desperation and alienation of the modern male. It's not. It's a f**kin' heist movie! It's as simple as that. These are the rules of the heist movie." At all times, O'Rowe's emphasis is on story-telling. To listen to him is to realise that the distance between epic and trash, between Homer and Tarantino, is bridged in a jump cut. "If it feels like I'm commenting on society - it's definitely not about that. It's just to keep the story going - to keep it moving."

If momentum is, then, the guiding principle of a Mark O'Rowe play, the monologue has become his chosen form - even if he contrasts it, routinely, with the "huge complexity of a proper play".

"A lot of people don't like the monologue play and don't think it's actually theatre . . ." he says. "And it sort of isn't. I understand where they're coming from. Because theatre is people talking to each other and there's a fourth wall and we look through it as we do a TV screen. A monologue is direct contact. It's somewhere between stand-up and direct theatre. For me, the stories I've been coming up with are just so big, with hundreds of characters and many locations and all that kind of stuff, you couldn't write Terminusas a movie. It's just that thing of the story requiring the form."

There is a certain impatience in O'Rowe's dramaturgy and, perhaps, in the man himself: the frenetic jive of his words, his plays that begin on the stage but which reach for the mind's eye, the scenes that must change every few seconds. (Even our interview takes place in three distinct sections: at a table, outside for a smoke, propped against the bar.) The mythologies he grafts onto his Dublin - the Mayan legends of Howie The Rookie, the kung-fu codes of Made in China- seem less derived from Irish culture than from Xtra-vision rentals.

But O'Rowe wants both: a play that moves with the logic of film narrative, where social culture and pop culture coalesce; his characters may exchange Asian curses, then hop on the 123 bus, murder a stranger, then deliver a rhapsody to junk food. Terminusis certainly violent - O'Rowe can anticipate walkouts at one grisly moment - but it is mainly a thrillingly unreal violence. If Crestfall, the least favourite of his plays, was an unremitting nightmare ("It was incredibly, incredibly dark and I'll never write something like that again"), is the fevered dream of Terminuswhat his career has been building up to?

"It's probably my most plot-driven play," he says. "It's not something that comes to me easy, plot . . . In terms of building up to this, I hope I have further to go."

Although the intricacy and rules of the verse mean that Terminusalmost comes with an in-built director, the production marks O'Rowe's directorial debut. "I've always wanted to direct and I've kind of been scared to," he says. "You're slightly on the outside of the rehearsal room as a writer and you feel quite vulnerable. You don't have - or you shouldn't have - direct contact with actors. You're watching the thing be filtered through someone else's sensibility." O'Rowe, whose plays have met with such gifted directors as Garry Hynes and Mike Bradwell, has rarely had an unhappy production experience, but, like the epic poets of old, he seems to want to possess the telling of the tale himself. He confesses that his early rehearsal period was spent learning to trust the actors, who, he now understands, know his world better than he does.

"What they've found is not what I wrote," he says. "It's actually way better." O'Rowe seems to be in a good mood, and there are now a few people around, so it seems like a good time to chance one last question. How did he get that chipped lens and that nasty-looking dent in his head? He points to his head: "I'm losing my hair, right, so I always get injured here. And I have two kids under five." His glasses, he reports, have a tendency to slip off the shower ledge.

As a Mark O'Rowe story, this just won't do, and he seems genuinely apologetic. "That's it," he says. "It's as banal as that . . . Sorry how boring that is."

Terminus opens tonight at the Peacock Theatre and runs until July 7