How well do you know your friends? And how much do you care? As Oscar Wilde’s best-built frivol opens, one of the smartest among London’s smart set has just discovered that his droll chum Ernest seems actually to be named Jack—and the mischievously guilty explanation, once it trickles out, positively delights him.

That’s the charming thing about Earnest: It’s chock-full of brazen deception and shameless manipulation, rather like Washington, only unlike in Washington no one cares in the slightest when they get found out. The servants confess blithely to drinking the master’s Champagne, and gentlemen invade one another’s country homes, declining to leave until they’ve done the monkey business they came to do. It’s probably the sense of entitlement that makes it all so funny: Each malfeasance gets launched in the open, with precious little pretense of righteousness, by a player who’s got only one aim—amusement—in mind. If you could buttonhole Jack or his layabout friend Algernon to suggest there’s something disreputable about their cavalier pursuit of diversion, they’d goggle at you in well-bred amazement and ask something like, “Whatever else is an overbred, undereducated leisure-class Larry to do with himself?”

Wilde’s marvelously mannered comedy—supposedly a near-indestructible edifice, to the point that it’s been called “the perfect play”—can in fact come rapidly apart if directors forget how crucial the question of style can be. Witness the broad, vulgar production mounted (and humped, and otherwise assaulted and abused and disheveled) at Arena Stage back in 2004; witness the preening, camping, squealing, and otherwise grating all-boy version done at the Source a few years before that.

So it’s something of a relief to discover that director Dorothy Neumann hasn’t felt the need to second-guess Wilde. Her crisp, unfussy, and blessedly fleet-footed staging for the Keegan Theatre’s no-frills New Island Project feels nicely attuned to what makes this play work: a delicate but crucial balance of solemn nonsense and playful seriousness.

Because make no mistake, Algernon and Jack—and the equally entertaining women they wind up pursuing—are deeply serious about their silliness. “Produce your explanation, and pray, make it improbable,” demands Algy when Jack-Ernest’s name game first makes itself apparent, and the fact that Neumann has Michael Innocenti’s insouciant, piano-playing Algy provide a musical punctuation for said explanation just points up one of the play’s central gambits: These are people for whom style and wit aren’t just the garnish on a conversation. They’re the pointEarnest, of course, is that in inflating the ridiculous, he’s also managed to make it pretty sublime.

He does that largely with his signature epigrammatic dialogue, which keeps that all-important banter percolating along. “The truth is rarely pure, and never simple,” Algy says killingly, when Jack dares to claim that he’s put something plainly. And in one early passage, even the servants in their fashionable bachelor establishments get in on the act: “I have only been married once,” Melissa Hmelnicky’s unflappable housekeeper says with a hint of disapproval, as if she’d been accused of a secret penchant for dull domesticity, and “that was in consequence of a misunderstanding between myself and a younger person.”

Domesticity, of course, is what Wilde’s lead foursome is pursuing, though for them you can’t imagine it ever quite becoming dull. Algy’s cousin Gwendolyn (Erin Buchanan) conceives an admiration for Jack, but only because she thinks his name is Ernest, and in any case their union hasn’t quite won the blessing of Gwendolyn’s famous Gorgon of a mother, Lady Bracknell (a deliciously snappish Barbara Klein). Algy, meanwhile, conceives an instant passion for Jack’s pretty young ward, Cecily (a perfectly pert Suzanne Edgar)—who returns the favor, chiefly because Algy has appeared at Jack’s country estate claiming to be Jack’s notorious younger brother, a famous if fictional wastrel named (you guessed it) Ernest.

Schemes ensue, not to mention betrothals, breakups, reconciliations, and highly improbable revelations involving nursemaids, novels, and mislaid handbags, all in pursuit of the thorough mockery of a Victorian ideal that Wilde actually has the impish nerve to make a character state explicitly, late in the game: “In matters of grave importance, style, not sincerity, is the vital thing.”

The thing is, he has her state it so amusingly that you hardly notice that he’s teasing. Mostly.