Alyssa Wilmoth Keegan stars in the No Rules Theatre Company production of Sarah Ruhl’s “Late: A Cowboy Song.” (Second Glance Photography)

“Late: A Cowboy Song” is an early work by Sarah Ruhl, now well-established through “The Clean House” and “Dead Man’s Cell Phone” and a MacArthur “genius” grant as one of the country’s top playwrights. It’s a loping, poetic little three-character doodle about a man and his wife — mainly his wife, for the husband’s a dud and the woman, lost and lonely, is mysteriously drawn toward a lady cowboy on the outskirts of Pittsburgh.

Ruhl fans moseying to the No Rules Theatre Company production at Arlington’s Signature Theatre will spot the author’s hallmarks. The plot is so fanciful that Red, the cowgirl, croons tunes to the moon while she strums her guitar (something Alyssa Wilmoth Keegan, as Red, manages with taciturn charm), and the whole thing is governed by an overarching bluesy whimsy.

Crick, the husband, is a dim ninny, and Mary, the wife, slowly discovers herself in a way that makes the 2003 “Late” feel like a skinny rough draft of Ruhl’s acute, uproarious 2009 “In the Next Room, or The Vibrator Play.” The main trouble with “Late” is the characters’ arrested development: Mary and Crick have been more or less hitched since second grade, and they’re still annoyingly childlike with each other. As Chris Dinolfo’s Crick and Sarah Olmsted Thomas’s Mary bicker and coo, the immaturity can be hard to swallow.

At first it seems to be a problem with Rex Daugherty’s direction, as if he’s pushing his actors toward infantilism and absurdity. But that’s where Ruhl wants these two characters. Of course, the hyper Crick might be drawn to the turgid depths of a Mark Rothko painting. Naturally, the cosmically perplexed Mary might find allure in Red’s slowed rhythms and open spaces.

The saving grace — for Ruhl’s plays are nothing if not graceful — is the way Ruhl imaginatively toys with her fairly cliched ingredients. Daugherty creates simple tunes with co-composer Kinsey Charles for Ruhl’s cowboy lyrics, and the show gets a nicely mythic Western effect from set and lighting designer Cory Ryan Frank. He neatly divides the small Ark stage, the smaller of Signature’s two spaces, between Crick and Mary’s messy kitchen and Red’s dusty prairie area, and a thin light panel runs horizontally across the back wall, suggesting blue skies and yellow moods, as needed.

Dinolfo’s performance is crisp and colorful, but he has an impossible part in the petulant Crick. Ruhl gives more soul to Red, here dressed in chaps and a 10-gallon hat by costume designer Lynly Saunders and nicely underplayed by Keegan. The questing Mary has the most latitude of all — she seems a lot like the puckish, wide-eyed wife in “In the Next Room” — and Thomas has a wonderful offbeat quality that blends sweet and sad without too much ado.

D.C. is Ruhl country: Woolly Mammoth has staged three major works, including the world premiere of “Dead Man’s Cell Phone,” and in 2005, Arena Stage bravely premiered her ambitious 31 / 2-hour “Passion Play.” “Late” may be lesser stuff, but plays don’t necessarily need to be great to be worth a look. Here as ever, Ruhl has a finger to her chin in poetic meditation, with the added attraction of a youthful yodel in her heart.

‘Late: A Cowboy Song’

By Sarah Ruhl. Directed by Rex Daugherty. Sound design, Brandon Roe. About one hour and 45 minutes. Through Jan. 19 at Signature Theatre, 4200 Campbell Ave., Arlington. Tickets $24-31. Call 703-820-9771 or visit