In the opening minutes of “The Black Wolfe Tone,” Kwaku Fortune poses a question that has been asked countless times: “Is mental illness genetic? Or: Is it a result of our environment?”

It’s a query that’s especially relevant in this one-act piece, which Mr. Fortune wrote and stars in; he’s the only performer who appears onstage, in fact, playing Kevin, a young man who has apparently been relegated to an asylum. Kevin’s first symptom, delusions of grandeur, seems evident as he greets the audience: “I created you,” he declares, and then proclaims, “I am a god … not a god, THE GOD!” 

Is this truly madness, though, or a clever playwright and actor knocking down the fourth wall, using Kevin as a vehicle to explore various issues of personal and social import? In the program, Mr. Fortune, who is Irish and of mixed race — his mother was born in Ghana — points out that “Tone” was inspired by an incident where he was “accosted on a bus by a heroin addict,” who, presumably based on the artist’s skin color, mistook him for a foreigner.

Another program note informs us that the play channels the spirit of Theobald Wolfe Tone, a key figure in the late-18th century movement for Irish independence. Kevin acknowledges him as “the enlightened Protestant forming the United Irishmen. Fighting for the downtrodden, for a better Ireland, for equal rights and equal opportunities for all! Never mind sex, race, or creed.”

If you’re expecting, at this point, that Mr. Fortune has concocted a self-righteous screed about the injustices that drive us all crazy, think again: “Tone” is quirkier and more compelling than that, offering an account of one individual’s distinctive struggles that carries wider resonance, and rather than preaching to a perceived choir, it encourages genuine reflection.

Under Nicola Murphy Dubey’s direction, the play, being presented by Fishamble: The New Play Company and Irish Repertory Theatre, also crackles with theatricality. Ms. Murphy Dubey arrives from her production of another new play at Irish Rep: “Irishtown,” a rather overheated farce featuring an ensemble that, while gifted, had clearly been primed to munch on the scenery.  

Kevin, as one might expect, is given to histrionics, but Mr. Fortune’s portrait is also disciplined and dynamically varied, so that the character can seem quite poised at times, not to mention funny. Appealing to the audience and to his doctor and interrogator, one PJ Cullen — the patient assumes the shrink’s identity at times, so that they can converse — Kevin drops witty one-liners and even assumes a plummy British accent at one point.

This comedian and impressionist also, predictably, vexes us with his outbursts; yet even recounting his more erratic and violent episodes, Kevin is more intriguing, and moving, than terrifying. We learn about his Irish father, “a man of love and life, of virtue, but essentially … absent,” and his mother, an “African … princess” who became the only Black person in their Irish town.

Race naturally figures into Kevin’s feelings of alienation and persecution; Mr. Fortune doesn’t underline this point, but it remains a powerful undercurrent as we learn of his experiences. Yet the play’s tone is not one of self-pity or defeat. The “big question,” Kevin finally resolves, is this: “Will I get better?”  

There are no easy answers, but Kevin realizes, “I need to do the work. I need to be honest.” It’s sage advice for all of us, and coming from someone who’s clinically insane — and/or uniquely aware of the madness surrounding him — it carries extra punch.