Brian Friel's "Dancing at Lughnasa" is a slight, sentimental play, but it's enjoying an evocative, tender production by the Keegan Theatre that's movingly well acted in the principal roles. The play opened Monday night as part of the Keegan's Irish Arts 2000 Festival.

Friel's tale, written in 1990, is essentially a gauzy memory play rising from the mind of Michael (David Jourdan), who was born illegitimate and raised by his spinster mother and her four spinster sisters, all of whom lived together in rural Ireland. When the lights come up he is onstage, well into adulthood and thinking back. The ensuing plot, if you can call it that, doesn't revolve so much as meander around the 1936 festival of Lughnasa, a pagan celebration of the harvest. The four younger sisters, all of them middle-aged, want to go to the festival and dance; the eldest says they can't--they're too old, she admonishes, and besides, it wouldn't be "Christian."

There are some minor dramatic diversions, such as the temporary reappearance of Michael's father and the presence of a dying uncle. But for the most part this is Michael's last recollection of the household before it disintegrates. And it's as a portrait of unhappiness--a la quiet desperation--that the production is most effective.

As Kate, the eldest sister, Maura McGinn presides over the household with the kind of forbidding, defensive and censorious authority that only deep-seated frigidity can express. And yet, and yet, she, too, still yearns to feel alive; but her self-repression, which McGinn ably suggests throughout her performance, won't let her.

Kathleen Coons gives Chris, Michael's mother, as full a range of emotions as the role will allow (and it's not much). Jenifer Deal threatens at times to steal the show as Maggie, the no-nonsense, hard-edged sister whose heart may be in the most pain. Sheri S. Herren and Melissa Flaim, as the other sisters, provide solid flanking support with their own distinct versions of desperation.

Michael is almost incidental to the plot, appearing infrequently as a stand-in for his childhood self. Not surprisingly, Jourdan plays him unobtrusively, as appropriate, subtly mixing his adult perspective with his youthful memories.

As the dying uncle, Kevin Adams doesn't have much to do other than wander in and out as his character charmingly loses touch with reality, which Adams does, well, rather charmingly. The one sour note is hit by Richard Montgomery, whose performance as Michael's father is an unconvincing caricature of a Welsh rogue.

Mark A. Rhea directs with a sensitivity that matches up with George Lucas's carefully detailed set, a faithful evocation of an Irish country kitchen, complete with soot marks blackening the plaster walls by the old stove. There is also, unfortunately, a thick nostalgia in the mood Rhea casts, which gives you the sense that this is a younger person's romanticized idea of how things were back in the old country in the old days, not how they really were.

But that mood is also in the script, which doesn't explore the reasons Michael is even having this recollection. Nor does it even give more than passing attention to what it may have been about these five women that left them unmarried and lonely. But with Friel the play is rarely the thing. It's the portrait and the colors he uses from his emotional palette. An acquired taste, to be sure.

Dancing at Lughnasa, by Brian Friel. Directed by Mark A. Rhea. Costumes, Pam McFarlane; lighting, Dan Martin; sound, David Jourdan. Through Feb. 6 at Warehouse Theater, 1021 Seventh St. NW. Call 703-757-1180.

CAPTION: David Jourdan, Sheri S. Herren and Jenifer Deal in the Keegan Theatre's "Dancing at Lughnasa."