Many opera plots border on the nonsensical but are given dignity by the music. Pretty much everything about Dominick Argento's one-act chamber opera "Postcard From Morocco" is determined but inspired nonsense, including its score. Performed as well as it was on Friday by the Maryland Opera Studio at the University of Maryland's Ulrich Recital Hall, however, it leaves you with a feeling that something unusually interesting and perhaps useful has been said.

Is it a parable on human frailty? Are the seven people gathered in a train station waiting room, each protectively clutching a box, really protecting their pretensions and fears? Does the opera's timelessness have some relationship to the two-dimensional figures that almost become part of the cast as they are moved around by a pair of wonderful mimes? And what do postcards or Morocco have to do with any of this?

People, sometimes in masks, move about as if in a dream. From time to time, two or three become marionettes. A small orchestra is onstage in costume and occasionally participates in the action. Sometimes what is going on is funny, and sometimes it is very touching.

The essence of this theater piece is ensemble, and ensemble is clearly the strength of this production. The cast is exquisitely balanced. Ellen Myers Kliman, Gretchen McNeil, Melissa Unkel, James Jones, Bryce Westervelt, James Hall and William Heim each draw their characters (or caricatures) boldly but subtly. They sing accurately and musically, and are wonderful actors.

Page Hernandez and Michele Sanchez are almost magically ubiquitous as compelling mimes, and the set and costumes are economical and effective. Robert McCoy conducts with poise, and responsible for all of these delights is Leon Major's inspired direction.

The program will be repeated tomorrow and Friday.