Caroline Stefanie Clay (Clementine) and Thony Mena (Reginald) in Forum Theatre's production of "Clementine in the Lower 9." (Melissa Blackall)

Post-Katrina New Orleans is the backdrop for Dan Dietz’s new drama “Clementine in the Lower 9,” and the hypnotic production at Forum Theatre features a jagged hole ripped through a wide roof. As the play’s blown-apart family tries to rebuild, that giant gash increasingly looks like the mouth of an angry god.

The scale is indeed that big as Dietz melds Greek myth with N’awlins disaster and superstition. The plot is loosely “Agamemnon,” and though it’s probably time for a moratorium on the trend of American writers adapting Greeks (“Oedipus El Rey” and “An Iliad” are two recent local examples), Dietz’s particular reach feels right. His dialogue is fresh and sassy, and the emotions run deep, thanks, in part, to an infusion of live blues music.

Scott Patterson plays the inevitable Chorus figure, and in addition to narrating, he occasionally sings and caresses the keys of an upright piano at one end of the Round House Silver Spring’s vast debris-strewn stage. (Lisi Stoessel designed the set, and George-Edward Burgtorf supplies a ton of props.) The earthy, mood-setting Patterson is the okra in the gumbo, and composer Justin Ellington’s foreboding music is as dusky and majestic as the starry backdrop behind the two-story 9th Ward ruin.

That dilapidated place is owned by a nurse named Clementine, whose 19-year-old son, Reginald, has returned from college in Manhattan. Jaffy, a jazz trumpeter and the family patriarch, has been struggling among the Katrina refugees in Houston, where he couldn’t find work. What he did find was a strung-out teenage girl, whose bizarre vision landed him a winning lotto ticket.

Back Jaffy comes to the bosom of his family, toting along the crazy addict named Cassy (meant to sound like Cassandra; the names are updates of the Greek originals). If you know “Agamemnon,” you wait in dread for where this is heading and for the truth about how Clementine and Jaffy’s young daughter really died in Katrina’s flood.

New plays bearing Greek myths are often uncomfortable or even unbearable as they slang up the classic. “Clementine” doesn’t stumble there. Whether stately or streetwise, the language flows easily.

“Apollo!” bellows the trancelike Cassy, unable to say anything else.

“Apollo can’t help you, girl,” Clementine snaps back. “Drink your [expletive] Gatorade.”

Director Derek Goldman’s actors are completely convincing. Caroline Stefanie Clay radiates maternal strength as Clementine, and Thony Mena shows a nice touch with prickly indignation as Reginald. Jeff Allin has a jazzman’s ease as Jaffy, and in the nearly wordless role of Cassy, Megan Graves creates a shrinking, spooky presence.

Goldman fills the big black-box space — which Forum routinely uses ambitiously — with strategically dim light, arresting underscoring, and acting that connects on intimate and mythic levels. The atmospherics are consistently in sync with the script.

Absorbing as “Clementine” is, it doesn’t quite nail its landing. Too little is made of Jaffy’s trumpet, even though the instrument eventually drives the family disaster. Also oddly, the show’s implications shrink from public to personal when Dietz drops Katrina and delves into drug addiction — Cassy’s and the recovering Jaffy’s.

That’s the “Agamemnon” demand for crime and punishment, which sits uneasily here, impressive as most of the evening is. Blame ancient Greece for pulling Dietz’s sharp eye and native tragic sense off bedeviled New Orleans.

Clementine in the Lower 9

by Dan Dietz. Directed by Derek Goldman. Music director, Scott Patterson; lights, Andrew F. Griffin; costumes, Ivania Stack. About one hour and 45 minutes. Through June 15 at Round House Silver Spring, 8641 Colesville Rd. Call 240-644-1100 or go to