The sound of a boiler, maybe a train, rumbles through the theater as a lone man sits silently. Lights dim, and the room closes in on itself. It's like an old Batman episode, without the camp. It's a dizzying display of artistic and technical cooperation, taking a back seat to the bittersweet romance in the rough-hewn reality of Love Song.

Paragon Theatre, which skates between classics and little-known work, has found the latter with John Kolvenbach's play, and it may be the company's best discovery yet.

Love Song balances rhapsodies with comic, harsh banter for an affecting, entertaining story. Joan and Harry are a professional married couple living and bickering with a pleasant intimacy.

"You oppose me for fun, Harry," she complains.

"That's called talking," he says.

It seems a very yuppie comedy of manners until Joan's brother, Beane, quietly enters their apartment. He's a little off. He may be autistic, shrinking from loud noises or assaultive questions. Improbably, he finds love - with a burglar who threatens him in his home.

Jarrad Holbrook directs a beautiful production, perfectly cast and performed and fully realizing the script's potential. While greater themes do emerge and linger after the play is over, Holbrook's production is grounded in character.

Emily Paton Davies plays Joan as a woman with a brittle insistence on routine that softens only with her brother. She's a middle manager who reacts to an intern's tears with anger at being inconvenienced. She curses, then uses old-fashioned words like scalawag and shenanigans. She's concerned with appearances but reacts to minor annoyances with threats of violence.

She and Scott McLean reveal a terrific intimacy as the married couple. There may not be a lot of romance left , but there is a lot of knowledge. McLean plays a husband amused by his wife's high- strung nature and, as in any marriage, they trade off idiosyncracies.

Barbra Andrews, a shrinking violet in The Glass Menagerie, is a stinking gladiola here as Molly, an anarchist burglar and malevolent imp. But when she meets Beane, she flicks a switch on him, bringing him out of himself and into the world.

Brian Landis Folkins is a marvel as Beane. He spends the first 30 minutes almost entirely self-contained. Only when Molly threatens him does a smile sneak across his face as he realizes his autonomy; she gives a philosophy to his aberrant behavior. They indulge in romantic interludes, reminding us how couples create their own mythology.

Love Song sees a world in which urban adults remain part of a family. Not only does Joan look after Beane, but they are clearly in touch with their mother. Unlike the world of sitcoms and movies, here people can live solitary lives and be connected to blood relatives.

bornsteinl@RockyMountainNews.com or 303-954-5101

Love Song

* Grade: A-

* When and where: 7:30 p.m. Thursdays through Saturdays through March 14, Crossroads Theatre, 2590 Washington St.

* Cost: $17 to $19; two-for-one Thursdays

* Information: 303-300-2210