Stephen Rea Photo by Ros Kavanagh

This co-production by Ireland's national Abbey Theatre and London's Royal Court Theatre features a stunning central performance by Stephen Rea as Eric, a Protestant loyalist born, raised, and still living in East Belfast, who, nonetheless, identifies as "exclusively and non-negotiably British." It has been some time since "The Troubles" in Northern Ireland have been set aside, at least officially, and life has become more-or-less normalized. But don't tell that to Eric, a man in late middle age who has spent most of his life immersed in a cesspool of unrelenting loathing of Irish Catholics, the "Fenians" as he contemptuously refers to them. "For four hundred years, they raped our women and burnt us out of our property," he says, with no hyperbole in his meaning or the vitriolic depth of his feelings about them, even as he adds as an afterthought that "we did the same to them."

When we first meet Eric, he is at a mental health treatment center for his initial session with his therapist, Bridget (Ronke Adékoluejo), a black British woman whom Eric refers to at first as a "nigger" before, eventually, getting around to self-correcting. And why is he there in the first place? It seems he has decided that his infant granddaughter Mary-May is a dead ringer for the longtime head of Sinn Féin, Gerry Adams, the defining object of every hate-twisted fiber of Eric's being.

At first, it seems as though the play will trace Eric's descent into delusion, follow his treatment, and perhaps lead us to his restoration to at least a semblance of normalcy. But his quirky suspicions about Mary-May's identity quickly become all-consuming and far more than either his daughter Julie (Amy Molloy) and his wife Bernie (Andrea Irvine) can begin to understand or cope with. When Bernie orders him to leave their home, he winds up in a park where he comes across another diehard loyalist, Slim (Chris Corrigan). Slim is half Eric's age, but he has been reared with the same bigoted worldview and still considers himself to be a terrorist for the cause, armed with a handgun at the ready. The match has been lit, and under Vicky Featherstone's no-holds-barred direction, the action continues to devolve to a truly horrific climax from which there can be no salvation.

If you can handle the pernicious content, you will surely find Stephen Rea's astonishing performance etched into your memory for a long time to come. Mr. Corrigan as Slim is nearly as powerful as Rea in depicting the unraveled mind of the unleashed soldier-of-war. Ms. Molloy and Ms. Irvine as Eric's besieged family members more than hold their own in trying to fathom the situation they are faced with, while Ms. Adékoluejo as the therapist represents her profession's calm and misguided self-assurance in its ability to undo a lifetime of traumatic brainwashing and savage encounters. The overall experience is abetted by David McSeveney's all-to-real sound design, Lizzie Clachan's deceptively simple set (watch what happens to the expanse of white carpeting over the course of the evening), and the absolutely essential services of both a fight director (Bret Yount) and a fight captain (Brett Anders). If nothing else Cyprus Avenue makes for a hell of a cautionary tale against unbridled xenophobia.

Cyprus Avenue
Through July 29
LuEsther Hall at The Public Theater, 425 Lafayette Street at Astor Place
Tickets online and current Performance Schedule: www.publictheater.org