Sex with minors likely remains our culture's biggest taboo. So thanks to David Harrower for having the guts to address the issue in a sophisticated way in this play -- and to City for having the guts to stage it.

Blackbird is not, of course, an "issue play." For one thing, it's about singular characters, not theoretical positions. For another, it takes place years after the abuse, when a young woman who might or might not be named Una confronts a man now named Peter, who had sex with her when he was 40 and she was 12.

Nor does Blackbird ever claim that the abuse was anything but; even Peter acknowledges that the act, for which he served six years in prison, was wrong.

Rather, what's potentially radical about the play is simply that it asks us to see Peter and Una as human -- to know them as more than abuser and victim.

Again, this is all by way of the playwright's job of telling a story, and exploring human behavior. But such narratives as they are told in real life are usually drawn in black and white, perhaps understandably, given the heinousness of the crime.

Yet for audiences prepared to handle it, Harrower offers a one-time abuser who is not a monster, but a man full of regrets. And he gives us a victim who, though though she still bears scars some 15 years later, has begun tentatively to regain control of her life.

Perhaps more radical still is Harrower's intimation about the cause of those scars: not the sex act itself, but a psychologically fraught misunderstanding between an adult man and an adolescent girl.

Blackbird, smartly directed by Stuart Carden, takes place in a single 80-minute act in the break room of an anonymous suburban office building. (The note-perfect set is by Tony Ferrieri.) It features intense performances by Robin Abramson and Steve Pickering.

As of this writing, there are three more performances, at 5:30 and 9 p.m. tonight and at 2 p.m. tomorrow (www.citytheatrecompany.org).