Watch the trailer for In the Red and Brown Water

Tarell Alvin McCraney might be a playwright, but he should really write a manual: How to Succeed, the Faux-Naïf Way. He’s explaining how he put acting aside to write The Brothers Size, one of last year’s critical hits in both London and New York. “I just thought, ‘I wish I had a part where I could bring all of myself to it - not just the proper English-speaking self, but the weird, loony, mercurial stuff.’ I thought, ‘Somebody should be doing this.’ And then I thought, ‘Oh! I should do it!’”

It is a rather simplified take on the route that led Miami-born McCraney to have two more works debut here this autumn: In the Red and Brown Water at the Young Vic, then Wig/Out at the Royal Court, while The Brothers Size returns to the Young Vic, then tours. It also cuts out the award-winning spell at Yale, and mentoring from Peter Brook. Still, in one sense, the speed-up is justified: he turns 28 this month.

In the Red and Brown Water succeeds The Brothers Size in McCraney’s Brother/Sister trilogy - relocating Nigerian myth to the heat of contemporary Louisiana. Spirits and gods become African-Americans at the bottom of the social heap, in the projects. The writing is a verse-like take on modern slang and patois - and the result is poetic, potent and funny, punctuated with music and dance. (Wig/Out, which has just opened to rave reviews in New York, is set in the transvestite ball scene.)

Despite the pressure around him, McCraney is almost unnervingly calm and polite. He answers questions at length and rarely loses eye contact. The only thing that sets him off course is an unfortunate pain au raisin, which has each of its raisins plucked out, one by one. Intense, perhaps, but intensity is sometimes necessary. While, for some, the stage has become a means of supporting a cause, for McCraney theatre itself is the thing to fight for.

When asked who his audience is, he says he writes for everyone - but for him, who grew up in one of Miami’s toughest neighbourhoods, there is a vital elaboration. “It’s important to engage people who feel they don’t have a voice in the theatre - because someone had the wherewithal to do that for me. Someone did something one day on a street corner, and that’s how I got into theatre - I got into a programme for the children of drug addicts. It changed my life, and without that I don’t think I would be here - well, especially not here [we’re in an arts centre off a leafy London street]. To be honest, I might not be alive.” He draws on experience. His mother died a few years ago after battling a serious drug addiction; a younger brother has just got out of jail.

So he moved into doing guerrilla theatre, performing on local streets, before winning a scholarship to study acting at university. Yet, acting isn’t even his real passion: dance is. But his father, with whom he lived after his mother became ill, only allowed acting. How come? “Well, Wesley Snipes was an actor, so that was okay. . . But I didn’t see Wesley Snipes in no pointe shoes!”

Suffice to say, McCraney’s and Snipes’s paths have since diverged. For one thing, Snipes doesn’t claim much influence from Lorca, Brecht or Peter Brook, for whom McCraney auditioned - before sending him his written work, and receiving encouragement. By the time he reached Yale School of Drama, acting had receded, though he’d got plenty of work in the meantime. But as he talks, with the same eloquence and gestures as his characters, it seems logical to ask if he acts in his plays.

“I try not to. Sometimes directors woo me, and I’m always on the precipice. But. . . acting is really hard!”

And writing is easy? “Not easy, but I have a way of working into it that doesn’t hurt me so much. With acting, you have to bring so much of yourself into the now. That’s hard for me sometimes.”

Yet it’s not as if his writing holds back. It may be stylised, but it relates to something gritty and relevant today: those marginalised by society, and by the theatre, too. Writing plays, it transpires, isn’t merely to exhibit that “weird, loony, mercurial” side of his. Concerning Oya, the heroine of In the Red and Brown Water, he points out the painful truth. “There are tons of plays about kings and queens and people in Russia, but there are not that many about black women - especially dark-skinned black women - especially poor, dark-skinned black women.” It would be great to say he was wrong. Of course he’s not.

He claims, however, that any political dimension is incidental. You can well believe him: he is mainly preoccupied with his craft, “obsessed” with Shakespeare, reading “tons” of Chekhov, making all those kings and queens and Russians inform his own characters. The problem is, this doesn’t bode well for his personal ambitions - he would, he says, put it all aside to have “like, 90” children. True, perhaps, but it’s so patently at odds with all he’s set to do. “The theatre I write has to have a necessity,” he insists a little earlier. It’s a necessity, it seems, that has entrapped him - until the next happy career change, that is.

In the Red and Brown Water, The Young Vic, SE1, until Nov 8; The Brothers Size, The Young Vic’s Maria theatre from Wed until Nov 8, then touring; Wig/Out, Royal Court, SW1, from Nov 20

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