Crushed beer cans or discarded playing cards? It's a tossup as to which pile of trash will outnumber the other on the set of "Tattoo Sky," the brash, poetic but ultimately unsatisfying drama written and directed by Eric Lucas.

In describing his goals for this piece, the second new play the intrepid Keegan Theatre is premiering this month, Lucas has invoked the name of Sam Shepard, and accordingly, designer Stefan M. Gibson has, perhaps too eagerly, evoked a kind of cowboy-inflected Western seediness sometimes associated with Shepard's plays.

The Nevada room in which the play unfolds has the cheap wooden walls of a low-rent motel, with pizza and doughnut boxes littering the floor. Perched on a bench, a saddle and gun lend the mess an aura of ominous machismo. Unfortunately, it's all window dressing, since this play, about two people tearing each other apart as they wait to swindle a third character, doesn't ground its images in believable relationships.

Camped out in an isolated house in the desert, "Tattoo Sky's" central characters -- the trashy but romantically yearning Ray (Mark Rhea) and Meg (Susan Marie Rhea) -- engage in fierce, desperate conversations, taunting and tormenting each other as they wait for the mysterious stranger they are conspiring against.

Though spirited and sometimes comic, the couple's slangy skirmishes don't lead anywhere emotionally, thematically or plot-wise. The same goes for the threatening remarks of an enigmatic figure named Taylor (Kevin Adams), whose entry into the house via the broken screen door is bad news for all concerned. But Lucas has a flair for language, particularly monologues, and the play ignites when it reaches one of the vivid speeches in which characters recall moments from their pasts -- a vicious dog fight; the teenage Meg's drunken epiphany on top of a bar's pool table; Taylor's memory of Sicilian fishermen slaughtering bluefin tuna that move like "a leathered sea, rippling, muscle and bone."

Unfortunately, as so often is the case, Lucas's strength is also his weakness. His way with words can lead him into cheap jokes, such as when Ray and Meg argue about whether "myopia" is a condition or a country. Without a doubt, his strengths are the monologues, with their bursts of hard-boiled lyricism. It is through them that one glimpses the imaginative world he's trying -- mostly unsuccessfully -- to reveal.

This world is a brutal one (the play kicks off with a shotgun blast to a television set). And Lucas manages to intensify the atmosphere of barely restrained violence with moments like the menacing sequence in which Taylor chats to Meg while suggestively skinning an apple with a knife.

Of the cast, Adams gives his character the most nuance, exuding a jovial creepiness. As Ray, slouching around the stage with his injured leg bound with duct tape in lieu of bandages, Mark Rhea is surly in a sort of stunned way. Susan Marie Rhea, as Meg (who tosses those playing cards on the floor), is more animated, but both actors fail to make their characters' bond authentic enough to support the play's crucial final shift from naturalism to a romantic spiritual reality.

"Is this what we've come to?" Ray demands of Meg at one point. "The words we speak, nothin' but a contract to be broken down? Ripped apart and taped all back together again. . . ."

Despite occasional sparks, it is indeed what this play has come to: shards of Shepard, taped together.

Tattoo Sky, by Eric Lucas. Directed by Lucas. Set, Stefan M. Gibson; lighting, Dan Martin; sound, Tony Angelini. Through July 8 at the Clark Street Playhouse Theatre, 601 S. Clark Street, Arlington. Call 1-800-494-8497 or visit www.boxofficetickets.com.

Kevin Adams, top, and Mark Rhea play seedy characters in an isolated Nevada house in Eric Lucas's new play, at the Clark Street Playhouse.