Outside, the melting pot of Adams-Morgan stirs with the sounds of a late spring evening -- cars and buses rumbling through the streets, a medley of languages on the sidewalks. But inside the converted auto body shop in an alley off Columbia Road, beneath a lighting grid mounted in the rafters where there was once an engine-hoisting rig, it is quiet, except for the occasional sound of man's voice urging his group to stretch and bend and run in place, to "curl into melons," then uncurl and leap toward the ceiling.

The man, Larry Alvord, spends his days teaching physical education in the Montgomery County schools, but this is not an exercise class, the flabby gathered together to shed inches. Alvord is an actor and this is the Prism Theatre Ensemble struggling to bring its dark comedies to light.

The six members of the ensemble are not weekend hobbyists. Prism lets them try their wings, see if their gifts are strong enough to give up daytime jobs like teaching phys ed for a life on the stage. Tonight they are rehearsing Samuel Beckett's Play and David Mamet's The Duck Variations (presented through June).

Director Matthew Coughlin sends Alvord, Caroline Steinhoff and Lorraine Pollack off to the far corners of the theater to "find the dominant traits" of the characters they play in the Beckett drama, in which three heads protruding from funeral urns torment themselves with the might-have-beens of the love triangle they formed in life. Coughlin wants his actors to put themselves into a trance-like state, a kind of self immolation that provokes an observer to confront his own emotions.

"All you've got is words," says Coughlin, tugging at his red-brown beard. "If you don't know what's behind them, nothing will happen."

Ressembling, the three actors squeeze onto two folding chairs, entangling themselves likes snakes. Coughlin hovers over them, a benign Svengali. "Say the lines," he says.

"I want you both," Alvord tells the two women.

"What can she give you?" Pollack taunts. "You need me."

Steinhoff ignors her, blitzing Alvord with shy tenderness. "Safety and security," she says.

"Need," Pollack urges, the temptress flashing her eyes.

Coughlin claps his hands sharply. "No expression," he commands. "Convey incredible violence but do it dead-pan." The actors glare at one another in a complex of suppressed emotions.

In Mamet's The Duck Variations two old men -- Emil, played by Ron Mulligan, and George, played by Coughlin -- sit on a park bench discussing ducks. Ducks are much like men, they conclude: They are born, procreate and die. But ducks can also fly, while men cannot. In a migratory flock the lead duck becomes a kind of existential hero.

From the terse script the actors construct identities for Emil and George. They live in the same retirement home and have been friends for years. George drinks; Emil is abstemious. George complains; Emil is resigned.

The two actors get into character and putter around the theater, laboriously going about their daily routines, heading toward the park bench conversation that Mamet's text portrays. Emil loses his glasses. George helps him find them. George has had no mail. Emil sympathizes with him. "Let's go to the pond and look at the ducks," George suggests. Except for the National Zoo, which is closed for the night, there are no ducks for miles.

Testing their new identities, Emil and George struggle to open the theater's heavy sliding door and shuffle out into the alley. At the top of the alley, they pass a line of people waiting to get into the Omega Restaurant. The women in the line took away, ignoring them, but several men frown in distress at the sight of two young men hobbling along and wheezing, discussing the problem of hiding George's whiskey from his nurse.

In Kalorama Park Emil and George peer into the darkness, searching for ducks. Four young men stand near a picnic table drinking beer. The rock group Pink Floyd throbs on their transistor radio.

"What do you think?" George asks.

"No ducks," Emil answers.

George nods sadly."No ducks," he says.

They turn to leave the park. "The blue heron is the enemy of the duck," George says. "In a way, the duck exists only to be eaten by the blue heron."

Emil nods. "And us," he says.