The line between right and wrong, good and evil, is sharp, dark and unequivocal in David Harrower's unsettling drama "Blackbird." It has to be.

A male-female sexual relationship frames the internationally acclaimed piece, but the play is about numbers -- 12 and 40. Those were the respective ages of neighbors Una and Ray when they engaged in a furtive physical affair. The emotional chaos during the "romance" and the devastation of both lives after it ended was a classic illustration of why we forbid such liaisons.

The idea of a middle-aged man with a pre-teen girl is so repugnant, we want to slam the door on it and not consider all of the messy nuances and implications that accompany such a taboo situation. "Blackbird" opens the door, and the compelling Renaissance Theaterworks production of the drama kicks us in the stomach, just as it should. The show recently opened in the Studio Theatre at the Broadway Theatre Center.

Playwright Harrower set his theater piece 15 years after Ray was convicted of his sexual contact with the girl. A prison sentence was served, and he changed his name in a quest to build a new life.

Therapy has done little to soothe the restless Una's crippled spirit and tormented soul. Now in her late 20s, she has tracked Ray to his workplace, and the entire 70-minute, single-act play unfolds in real time in a shabby break room littered with the remains of snacks and lunches. There Una confronts the man who took advantage of her girlish naivete and appetite for attention.

Originally staged at the renowned Edinburgh International Festival in Scotland, "Blackbird" was the buzz of London theater in 2007 when it beat out such dramatic heavyweights as Tom Stoppard's "Rock ‘n' Roll" and Peter Morgan's "Frost/Nixon" to win the prestigious Laurence Olivier Award for best new play. A subsequent off-Broadway staging in New York received critical raves, and the drama has been receiving numerous regional theater productions.

While emotional fireworks continuously flare and fade in "Blackbird," the audience is drawn into analyzing the two characters. Ray insists he is not a serial sexual predator and says has not pursued other underage girls. But it appears he has not been entirely honest with himself about the affair with Una, and that makes us wonder about his propensity for denial.

We also question what Una wants from this confrontation. Does she even know? As their meeting tilts in one direction, then another, we better understand the layered complexity of many human interactions and the contradictory behavior that so often results.

"Blackbird's" subject, intensity and overlapping staccato dialogue evoke two better known playwrights, David Mamet and Neil LaBute, but this is no second rate imitation. It courageously stands on its own.

Renaissance Theaterworks regularly tackles gritty plays and tough topics, and co-founder Susan Fete is the go-to director for them. Here she places actors Brian Mani and Carrie Coon in a claustrophobic box of a set, designed by Nathan Stuber, that is smaller than the Studio Theatre's compact stage. The fourth wall appears to have been crudely sliced away, enhancing the sense of voyeurism experienced by the audience during this uneasy encounter.

The break room is cheap, tacky and scuffed, a visual metaphor for the tawdriness of the affair that occurred 15 years earlier.

Mani brings a masculine everyman quality to the character of Ray, making him likable and deepening the mystery of his past conduct. Is he really a pedophile? There is nothing strange or creepy about him.

Playing Una, Coon is required to have an exhausting palette of emotions accessible on a moment's notice, and she does. It has been exciting to watch this talented young actress grow from her student acting days at the University of Wisconsin-Madison to working professionally at the American Players Theatre and the now defunct Madison Rep.

In this play, Coon displays a tightly coiled anger and desperation that can melt into a heartbreaking vulnerability. The transformations are real, and our reactions are earned.

The new year may be only a few weeks old, but my hunch is that "Blackbird" will be among the elite theater experiences of 2010. The story and characters follow you for days after the final curtain.

"Blackbird" runs through Feb. 7.

New boss Up North: Door County's American Folklore Theatre, the company that has developed such hits as "Guys on Ice" and "Lumberjacks in Love," has chosen Dave Maier to be its new managing director. He replaces M. Kaye Christman, the company's first managing director, who is retiring after 12 years of service.

Maier, who lives in Sturgeon Bay, has a long theater resume. He is a graduate of the prestigious American Conservatory Theater's advanced training program in San Francisco, and he spent 10 years with the A.C.T. as an actor, director, conservatory trainer and literary coordinator. Maier was also managing producer of the A.C.T.'s new plays program, where he worked with such writers as Anna Deavere Smith and David Budbill, and he was co-founder and artistic director of the Encore Theatre Company in San Francisco.

He has spent the last two years working as the American Folklore Theatre's assistant managing director. Maier moves into his new job next month. Jeff Herbst remains as artistic director.