A good set reflects a mind-set. Behold, for example, the illuminating clues in designer James Wolk's drawing room for "The Constant Wife" at the Olney Theatre Center.

The decor for W. Somerset Maugham's 1927 comedy is as tasteful, spotless and modern as the streamlined thinking of Constance Middleton, the unflappable spouse of the title. Given the period, Wolk and director John Going could have saturated the household with chintz and bric-a-brac, yet that wouldn't be Constance, who, as embodied by Julie-Ann Elliott, is a model of efficiency and discretion but never convention.

And the conventions of marriage are very much under review from the moment we meet Martha, Constance's scowling sister, who's ready to fling the mud of scandal. Seems everyone but Constance knows that her husband is having an affair -- and worse, he's carrying on with Constance's best friend, Marie-Louise (a frothy Ashley West). Martha, played in a state of wide-eyed censure by Allyson Currin, thinks Constance should know.

To tell, or not to tell? As the merits are parsed, Maugham warms up the audience for the twists, one of which involves the arrival of Bernard Kersal, a slightly bland but sweet bachelor whose flame for Constance has burned for years. There's your rooting interest: Surely Constance might strike a spark with courtly, handsome Bernard, nicely rendered by John Wojda as a dashing teddy bear. (This being a progressive marital comedy -- whiffs of Wilde and Shaw, who did this sort of thing with more panache -- all the men are essentially ninnies.)

Then there's the fact that Constance is nearly impossible to surprise. She verges on omniscience, yet tends toward offbeat forgiveness even amid circumstances ripe for wifely vengeance. This keeps everyone around her off-balance while endearing her to the audience; no wonder the part, originally played by Ethel Barrymore, has been embraced over the years by the likes of Ingrid Bergman and Katharine Cornell.

Elliott, gliding amid the ivory-upholstered furniture and delivering quietly radical speeches on the bargain that marriage imposes on men and women, couldn't be breezier. Her bemusement sets a merry tone that's seldom shaken, since the men cannot be taken seriously when they finally go apoplectic. Even allowing an extra degree of explosiveness -- the part of Marie-Louise's outraged husband was being read this past weekend by a last-minute replacement for an injured actor -- the show is designed to retain its tranquillity. That's Maugham's trick: Constance rocks the boat yet keeps an astonishingly even keel.

The supporting cast pitches their performances accordingly, with Currin, Helen Hedman (a shop owner who offers Constance a partnership), Nancy Robinette (Constance's epigram-ready mother) and Michael McKenzie (the dapper, philandering husband) all gamely striking out against Constance's newfangled logic. In Liz Covey's costumes, they're a fetching assembly, with flapper dresses and tight caps for the women, plus unusually interesting suits for the men -- well-tailored, and with subtly appealing colors for Wojda's Bernard.

The sophisticated milieu is welcome. Bucking theatrical trends, Going and company don't belabor the obvious and don't trap Constance amid overplayed dolts, nor do they create an arid/stifling atmosphere for their heroine to bravely escape. Instead, they manage the affair as Constance would: with a muted but impeccable sense of style.

The Constant Wife,by W. Somerset Maugham. Directed by John Going. Lighting design, Dennis Parichy; sound design, Jarett C. Pisani. Approximately 2 hours 20 minutes. Through March 11 at Olney Theatre Center, 2001 Olney-Sandy Spring Rd. Call 301-924-3400 or visit http://www.olneytheatre.org