The subject range of contemporary opera -- what there is of it -- would sometimes seem to lie somewhere between the relative mildness of moral depravity and the extreme angst of Armageddon. Thus it is particularly pleasant to come upon a stylish and worldly work like Dominick Argento's "Postcard From Morocco," which was presented in an appealing production last night at the Wolf Trap Barns by the resident company.

Not that "Postcard" is all fun and games. It is one of those circumstantial dramas, like Thornton Wilder's "Bridge of San Luis Rey," in which strangers are brought together by accident in an isolated place. In this case, the setting is a Victorian railroad station in some exotic land. Seven persons are waiting for a train: a lady with a hand mirror, a lady with a cake box, a lady with a hat box, a man with old luggage, a man with a paint box (Mr. Owen, the only character with a name), a man with a shoe sample kit, a man with a cornet case. The ostensible subjects of their exchanges are the contents of their luggage. These contents, which they guard intently, end up taking symbolic significance for the secrets the individuals guard in their psyches.

And if all this sounds a little cryptic and precious, it seems less so in performance, tightly squeezed into a single act that lasts about an hour and a half, beautifully staged here and set to music of considerable fluency in a kind Brittenesque manner.

Playwright John Donahue explains in the program: "We see each one trying to protect whatever small part of himself he has in his suitcase, the symbol of his secret or lack of secret, his dream or lack of dream. It is through the actions of these waiting creatures that we see our own fears and anxieties along with the fierce way in which man protects himself from the stranger." Well, this kind of material obviously can get pretty tedious. But the frequent potency and imagination of Argento's music ameliorates that. The score is packed with terse arias and ensembles of considerable stylistic range. It varies from a wrenching final monologue by Mr. Owen, strongly sung by John La Pierre to droll quotes from Wagner's "Ring" and "The Flying Dutchman," and a spell of what sounded to me like ragtime. All are in a considerable variety of harmonic styles.

Each of the singers was impressive. Enunciation was not uniform, but at least three singers were always understandable, which is a necessity in this complex text. They were La Pierre, Gordon Hawkins (what a rich, creamy voice he has) as the man with shoe samples and David Lowe as the man with old luggage.

The women were less clear, but all three sang beautifully: Jeanine Thames as the lady with the hand mirror, Phyllis Treigle as the lady with the cake box and Victoria Livengood as the lady with the hat box. Richard Woitach conducted with style.

Linda Brovsky's direction, Jeffrey Schneider's sets, Helen Rodgers' costumes and Peter Kaczorowski's lighting were all quite fine. There was a real early 20th-century ambiance, and one couldn't help thinking of "Murder on the Orient Express," especially at the opera's beginning and end, when gusts of steam filled the stage as trains arrived and departed. The production compares well with the version of "Postcard" given by the Washington Opera.

It is to be repeated tomorrow and next Thursday and Friday.