In Annie Baker's play "Circle Mirror Transformation," the games we play become one with the lives we lead. The play, genuine in a swell Theatre Horizon production with actors who understand every neutron of their characters, shows how a group evolves – in this case, five people in a community-center class that asks them to role-play, trade in identities and channel inanimate objects, all for fun.

But how long can you participate in that sort of psyche-bending activity without being changed in some way? If you're of a certain age, watching Baker's play may bring back memories of '70s psycho-drama sessions – in some places around Philadelphia, people went to them after work, much as they do now to weekly Quizzo games in bars. Group leaders would lay out situations and the audience would improvise their roles in these little fabrications. I never went but lots of my friends did, and they came back exhilarated and generally irritated. (Please don't confuse this with drama therapy, conducted by trained specialists.)

Psycho-drama is part of the course being offered to the four characters in "Circle Mirror Transformation," but so is movement, communicating in babble or phrases, reconstructing visual scenes of a childhood bedroom by getting participants to play the bed or the lamp and the sorts of games that people may or may not do in, say, college acting classes. The person giving the six-week class is the head of the New England community center where it's being held. She's a warm, down-to-earth woman and a quick-thinker, played with engaging precision by Nancy Boykin, whose every move, stare and nuance in her delivery defines and confirms our understanding of her character.

The woman's husband, James (Bob Weick) is in the class; he's a former lady-killer, now settling progressively into middle age, and with a teen-aged daughter who is driving him crazy. His other classmates are Theresa (Kim Carson), who's just moved to the town to escape New York and the boyfriend she's shed; Shultz (David Bardeen, a portrait of self-doubt), who has recently divorced his wife and is at sea; and Lauren (Emilie Krause), a high-school kid who has mastered the art of impetuous reluctance.

What happens when these diverse, somewhat broken people try to play together? In "Circle Mirror Transformation," they do what people do in ongoing groups – they become a team, uncomfortably but surely.

The most striking aspect of Baker's play is the way it pulls us into the group – we know nothing about these characters at the beginning, just as they know nothing of each other (except for the married couple, of course). Baker's script puts us directly into the group dynamic; by the end, we could be the ones standing up in front of the others to assume their characters. Still, there's no way that Theatre Horizon's co-founder, Matthew Decker, could have powerfully delivered this comedy-drama without a group of actors so keenly attached to the moment, just as the characters are goaded to be attached to their little exercises, which take place in a series of blackouts.

Decker's direction displays his understanding of these characters, as well – what they're trying to prove or not, how they go about succeeding and failing. He arranges them on Maura Roche's convincing work-out room set so that they're always aware of one another even as they sometimes wish they could become invisible.

Baker is probably not easy to direct – her stuff is edgy in all the qualitative meanings of that word: She twists conventional scene-writing, she's smart and inventive, and her characters can say quirky things that come off as fully believable. At the same time, she can be gratuitous – dictating excessive pauses in her scripts (the black-outs between scenes here may or may not be hers, but several are inexplicably lengthy), writing a play of nearly two hours without intermission, and giving it a precious name not easily parsed. 

By the end of the unconventionally formatted "Circle Mirror Transformation," we get an oddly conventional play. The game-playing is infused with truth-telling. The circle, if that is the circle in the title, is complete. And Baker puts us in the middle of the biggest game of all – we thoroughly know people who don't even exist.


"Circle Mirror Transformation" runs through March 16 at Theatre Horizon, 401 DeKalb St., Norristown. 610-283-2230 or www.theatrehorizon,org.