Theresa Rebeck is back and in good form at the Mark Taper Forum in a world premiere of “Poor Behavior.” The plot is the stuff of nightmares: two couples on a weekend vacation that devolves into arguments and adultery.

According to the program notes, Rebeck was inspired by a particularly nasty weekend of her own. Imagine being at a rented vacation home with some old friends and being wrongfully accused by a woman of an affair with her husband. From that bad experience, Rebeck has mined some theatrical gold.

To begin with in the play, Ian (Reg Rogers) and Ella (Johanna Day) are totally sloshed, but still manage a relatively intelligent argument about goodness. Ian, my husband assures me, is playwriting shorthand for arse and, indeed, Ian is a very smuggly British man with dark machinations.

Ian met Peter (Christopher Evan Welch) at his engagement party to Maureen (Sharon Lawrence). Maureen was once serious about Peter’s brother, but Peter feels that his brother dodged the bullet. Peter tells Ella, Maureen is “almost family,” yet Maureen is high strung and not particularly emotionally stable.

On this particular weekend, Ella and Ian stay up after Maureen and Peter retire. Ella cleans up and leaves Ian but Ian doesn’t go up to bed and this inspire wild accusations by Maureen. Peter then doesn’t actually deny Maureen’s suspicions of adultery and goes one step further. He doesn’t deny them when asked by Peter. And when asked to leave with his wife, he stays.

While on one level we understand  Ian as he tells to Maureen, “The public perception of our marriage is you’re a rampant nut case,” yet one wonders to what degree Ian has manipulated Maureen’s hysterics for his own narcissistic needs. Ian isn’t evil, but he’s a desperate, self-involved man and perhaps the whole concept of good and goodness eludes him.

The moral is that holding self-destructive friends close, can bring “soul-sapping” disaster  home. Has Peter been proudly smug, holding himself and his marriage above Ian, ghoulishly delighting in this train wreck of a relationship? Like a lookie loos getting too close to a train wreck, Peter and Ella become victims themselves. And by doing so, have then also been behaving poorly?

The ensemble are strong and the pace crisp under the guidance of director Doug Hughes. Day stumbled a bit on her lines opening night, but quickly recovered. Rogers as Ian was disarmingly charming, making Ian almost forgivably evil. Lawrence has a vulnerability as Maureen that makes you pity rather than despise her hysterics–particularly as we see Rogers’ Ian manipulate the events. Day’s Ella is the pragmatic person falling under Ian’s spell while Welch plays Peter as a slightly rigid but upstanding guy.

Rebeck commented in the program notes that “the definition of marrige as an essentially good institution…is problematic” but the play is really about “definitions of behavior.” And in one weekend, we see some darkly funny examples of “Poor Behavior” that will leave you laughing and hopefully relieved that you aren’t in that lovely country house on this particular weekend. “Poor Behavior” is wickedly funny but asks some scary, dark questions about the goodness, semiotics, marriage and just what is good behavior.

“Poor Behavior” continues until 16 October at the Mark Taper Forum.