Holly Twyford as 17th-century playwright Aphra Behn, with Gregory Linington in Liz Duffy Adams’s comedy “Or,.” (Grace Toulotte)

Is it the late 1660s in the poets-and-spies comedy “Or,” which at Round House Theatre gives us the ever-dashing Washington actress Holly Twyford as Restoration-era playwright Aphra Behn? Or does the post-Puritan sexual and political liberation wafting through the air smell just a bit like the 1960s?

The answer in Liz Duffy Adams’s popular play is often “both.” Adams takes scattered facts about Behn, hailed by Virginia Woolf as the pioneer who made professional writing plausible for women, and builds a juicy, nearly plausible fantasy about getting started as a writer after falling in debt as a spy (both of which really happened). It’s a thoughtful drama and a hilarious farce, a play popping with rhymed couplets and earthy ­f-bombs. It’s also a total feast for the three performers in director Aaron Posner’s swaggering entertainment.

With its lively language, quick changes and swinging spirit, this balanced ensemble serves up what may be the season’s top showcase of comic acting in a 90-minute breeze. Twyford is joined by her recent sparring partner in Ford’s Theatre’s “Who’s Afraid of Virginia Woolf?,” Gregory Linington, and by Erin Weaver, both playing three roles with hilarity and verve.

Which plot to start with, the espionage, or . . . ? Let’s say the romantic entanglements. The curious yet ever-independent Behn is juggling interests with King Charles II (Linington, displaying royal power with delighted ease) and with the madcap actress Nell Gwynne (Weaver, an infectiously happy sexual pirate in breeches and tall boots). When Behn’s former lover William Scott comes charging in, it leads to expertly arranged funny business, as Linington plays this role, too. When Charles and Nell ­Gwynne get an eyeful of each other, that’s more algebra for the farce.

Twyford is a superb center for the shenanigans. Her Behn is innately quizzical — the Restoration-style prologue outlines the ambiguities of the play’s title — yet she is absolutely set on achieving literary glory. Adams builds lots of guile into Behn, whose spying days are largely behind her as the play discovers her in jail, but Behn is also prone to confusion. The circumstances are nuts: Is Scott part of a plot to assassinate Charles? Behn has to get by on her wits, and Twyford’s blend of quick thinking and vulnerability makes this character an unpredictable, magnetic heroine.


Erin Weaver as Nell Gwynne and Holly Twyford as Aphra Behn. (Grace Toulotte )

Linington often seems to be in two places at once as the bemused Charles and the potential rebel Scott, playing both men with dignity and style. The tone of Posner’s show is always high, even when the antics are low: This is grown-up fun, never a slapdash goof. That’s true even when Weaver swans through in a scene-stealing appearance as Lady Davenant, a benefactor who might accept Behn’s half-finished play if it’s done by morning. Lady Davenant’s costume is designer Kendra Rai’s wackiest — the boots alone are a riot — yet it doesn’t remotely upstage Weaver’s brilliant, fast-talking turn as the prissy, bossy, loopy producer.

“Or,” which includes a comma in its title (meant to invoke two-titled Restoration comedies such as “She Stoops to Conquer; or, The Mistakes of a Night”), has been kicking around since its off-Broadway debut in 2009. Descriptions and photos often make stagings look like antic, off-putting cartoons: “Can’t be the easiest play to fire up,” Celia Wren judged in the Washington Post review of Rep Stage’s 2011 version. Posner’s show is rewardingly savvy at every turn, not least in Paige A. Hathaway’s set for Behn’s subtly hip apartment. Look closely at Behn’s wide, jampacked red room, vaguely like a dorm, and you’ll see scattered relics of the 1960s — a psychedelic Doors poster, for example. Even more critically, Hathaway pushes the set forward and wraps it around the actors, framing them smartly on what can be a too-open stage at Round House.

It feels right when Beatles music surges up and Twyford’s Behn writes like mad, ushering in a new theatrical age. It’s a delectable grace note in a highly verbal play, a piece that seems like a natural fit for this classics-saturated city. Or: Maybe it just feels natural because Posner’s trio plays it with such controlled abandon and freedom and joy.

Or, by Liz Duffy Adams. Directed by Aaron Posner. Lights, Thom Weaver; sound design, Christopher Baine. Through May 7 at Round House Theatre, 4545 East-West Hwy., Bethesda. Tickets $30-$60. Call 240-644-1100 or visit roundhousetheatre.org.