Although playwright David Mamet makes some telling observations about "A Life in the Theatre," this essentially two-character drama, revived by the Round House The- Theater ater in Silver Spring, tilts ever so distinctly toward the soporific.

Indirection has always been Mamet's method. His dialogue consists mostly of surface scratchings, suggesting, but never actually specifying, the drama underneath. The play's 26 brief scenes provide no more than glimpses, really, of the evolving relationship between a pair of actors onstage and off. One of them is a grand old man of the theater (David Cromwell), a creature of flourish and ego, who is heading into the sunset. The other (Gerry Paone) is a young whippersnapper, coming into his own.

For all the apparent minutiae of nights in the dressing room, something critical is going on, even if language only goes so far in capturing it. A balance of power and pride is shifting from old to young. It may be that a torch is being passed along. Any more than that you will have to intuit yourself from the passing chit-chat over the make-up table or one end of a muffled phone conversation.

We see the actors in rehearsal. We see them in the wings. And we see them performing snippets from a World War I potboiler, a hoary medical drama and a ludicrous scenery-chewer that has the two of them adrift at sea in a lifeboat and going out of their sun-baked minds. But it is indicative of Mamet's approach that he flips the usual perspective for plays within a play. Here the back of the stage is a curtain, which parts periodically to reveal blazing footlights and the great void that is the audience. So when Mamet's actors actually go onstage to strut their stuff, they are emoting with their backs to us.

In what may be the evening's most arresting scene, the young actor is rehearsing all alone on the bare stage. Suddenly, he senses that he is being observed by the older actor and they engage in a halting conversation--the one, bright in the spotlight's circle; the other, a disembodied voice somewhere out there in the dark. As an image for the flux and mystery in human relationships, the moment is stunning.

In fact, the physical production at the Round House is first-rate. Richard H. Young has designed an evocative backstage locale and lighted it with considerable expertise. Rosemary Pardee-Holz has provided a whole rack of appropriate garments, since the actors are constantly changing from street clothes to costumes. And Kathleen Wolfrey has rounded up all the mandatory props that a silent stage manager (Geoff Grob) sets up and dismantles with dutiful efficiency.

As the older actor, Cromwell is about 20 years too young for the part, which may account for an overall diminution of poignancy. But he has the character's shaky ego, his buried fears and his queenly narcissism down pat. Paone, as the heir-to-be, is especially good at indicating the insecurities that plague the over-confident. You will not doubt the reality of their relationship--director Jerry Whiddon has made sure of that--but you cannot deny, either, that it is elusive.

That may be the point. For those living a life in the theater, the fictions of the moment prevail. Personal traumas are momentarily submerged in the business of getting on with a show. Those traumas never go away, but you'll hear them only obliquely in the discussion, say, of how the night's performance went.

I can understand why actors would love this piece. The subtext is all. There are fewer rewards for an audience, however. The two lives in question are authentic enough, but Mamet has withheld so much that in the final count, they prove to be faintly--and disappointingly--uninteresting. A LIFE IN THE THEATRE. By David Mamet. Directed by Jerry Whiddon. Scenery and lighting, Richard H. Young. Costumes, Rosemary Pardee-Holz; properties, Kathleen Wolfrey. With David Cromwell, Gerry Paone, Geoff Grob. At the Round House through March 27.