Seen Off Broadway: What Lucy Thurber’s Scarcity has in abundance, at least in its first act, is a knack for wringing unexpected laughs out of uncomfortable class-conscious situations. (So uncomfortable, the Atlantic Theatre Company production opened to some savage reviews.) Tapping the same vein of trailer-park unease as Sam Shepard and Tracy Letts (Killer Joe), Thurber moves northwards, to the sticks of western Massachusetts, where the proud but continually challenged Martha (Kristen Johnston) rides herd on her drunken layabout husband Herb (Michael T. Weiss). Their two children, 16-year-old Billy (played by Squid and the Whale co-star Jesse Eisenberg) and precocious 11-year-old Rachel (scene-stealing Meredith Brandt) lose themselves in their studies and pastimes (like Rachel’s closely held tarot cards) as much as possible. Ellen (Maggie Kiley), a young teacher and a child of privilege, works with Billy to get him into an affluent out-of-town school. But the many subjects Billy’s family sweeps none-too-discreetly under the rug, like hazy Herb’s seemingly incestuous yen for his daughter and the strained co-dependency between Martha and her cousin, Louie (Todd Weeks), pile up like dust bunnies. That Ellen, who holds herself as tightly as Billy and his family let it all hang out, has a less-than-altruistic attachment to her pupil is a flashpoint as everyone gets a crash course in the struggle between the haves and have nots.

Material like this, which equates poverty with perversity and riches with repression, could easily fall into caricature. Walt Spangler’s carefully detailed set, with its rumpled couches, Iron Maiden records on display, and boiler in the corner, is full of obvious, if well-chosen, signifiers about life lived near the bottom rung of the ladder. The performers, though, are all bootstrappers; Johnston makes Martha’s striving, despite the long odds posed by her husband and her own worst inclinations, into something affecting, and the two kids, wary, conniving, and sympathetic by turns, are appealing. But in Act II Thurber and director Jackson Gay lose their bearings, and make the more weakly drawn (and weakly played) Ellen into a nightmare of condescending attitudes, which throws the production out of whack (and plays right into the pens of critics just waiting for the show’s high-wire act of satire and social observation to come tumbling down). And, like too many plays I see, the show ends two or three scenes early—I don’t mind a production that ends on an unresolved note, emotionally, but matters of fact, like the fate of one character, are left dangling. The author of Scarcity—and a whole generation of playwrights—needs to give more.

Giving their best efforts are costumer Ilona Somogyi, whose clothes range from pure roughneck (Herb) to out-of-element sophistication (Ellen) and sound designer Daniel Baker, who has a pungent score, by Jason Mills, to work with at scene changes. The talented Jason Lyons doesn’t have a lot to do except light the set in a sort of sickly-homey fashion. ( Hayden Productions provided the lights, One Dream Sound the audio and Tom Carroll Scenery the set construction.) At the end, however, as night fell on the set, and the prospects for at least one character, there seemed to be a flash of blue, a characteristically slippery touch for a play that isn’t easy to grapple with.