In Tennessee Williams's "A Streetcar Named Desire," Blanche DuBois says she wants magic, but director Steven Scott Mazzola and actress Amy McWilliams render her with more realism than usual in the Keegan Theatre's long, uneven but never boring staging at the Gunston Arts Center in Arlington.

That famous line of Blanche's--"I don't want realism. I want magic!"--usually stands as one of the play's summations, a compression of what the production has been saying all night long. But Mazzola and McWilliams haven't been saying that at all. Instead of a flighty, wily, ultra-feminine Southern belle dogged by the past and halfway to the loony bin, their Blanche is a worldly adult woman on the skids. McWilliams, who is consistently terrific even when the show wobbles, creates a tough and funny Blanche; I've never heard the character's bright, acidic wit so clearly or felt her mind--as opposed to her emotions--move so fast.

Mazzola seems to be systematically dampening the lyricism in Williams's writing in favor of creating more realistic characters, as if he's out to humanize dramatic icons. It's not a bad idea; the play is usually seen as a war between gritty, sweaty, brutish reality and idealized delicacy, with Blanche as a kind of performance artist spreading theater wherever she goes. McWilliams's Blanche still performs, of course, but it's subtle, which makes her a much more recognizable figure than usual. As a result, she utterly monopolizes the audience's interest; it's hard to remember that her nemesis, brother-in-law Stanley Kowalski, can dominate this play under certain conditions.

In that role, Mark Rhea gives an oddly muted performance. He was an effectively sullen Brick in the Keegan's staging of "Cat on a Hot Tin Roof" a few seasons back, but Brick is all about keeping himself bottled up, while Stanley is about letting it all hang out, forcing confrontations and smashing things up when he gets tired of words. Stanley is a constant threat, but Rhea is not. Nor is there any real spark or understanding between his Stanley and Brook Butterworth's Stella (who, like Blanche here, rather marvelously seems to age during the play), which leaves a pretty big hole in the show.

Lighting designer Daniel Martin puts a muggy-looking twilight haze over the stage, and set designer George Lucas manages the improbable feat of cramming the play's two-story New Orleans tenement into the none-too-tall black-box theater at Gunston. The supporting acting is solid, especially Ian LeValley's nervous, hopeful turn as Mitch, the man who temporarily falls for Blanche.

But Mazzola's leisurely, conversational pacing begins to take its toll as the show lumbers toward its 3 1/2-hour finish line. The tension ought to be rising--the last hour hardly lacks for drama--but Mazzola lets the actors linger over the lines interminably, especially when Mitch comes back for his final meeting with Blanche.

Right about then, you may find yourself wondering how McWilliams's hardy Blanche is going to crumble in time to make the play's ending work. The answer lies in two surprises that Mazzola has up his sleeve as he directs Blanche to make unfamiliar moves at the end of the last two scenes. You may or may not agree with the choices; since it would spoil the show to describe them, I'll only say that I liked the first, have doubts about the second, and was caught off guard both times. "Streetcar" fans will definitely have something to talk about on the drive home.

A Streetcar Named Desire, by Tennessee Williams. Directed by Steven Scott Mazzola. Costumes, Allen D. Smith; sound design, Tony Angelini; fight director, Michael Jerome Johnson. With Sheri S. Herren, David Jourdan, Joe Farella, Daniel Lyons, Lee McKenna, Kit Young and Pamela Jackson. At the Gunston Arts Center through June 26. Call 703-757-1180.

CAPTION: Mark Rhea and Amy McWilliams in "A Streetcar Named Desire."