Garrison Hull's first opera, "Nancy," commissioned and ably performed by the Opera Theatre of Northern Virginia, had its world premiere in concert form Friday at Gunston Hall. Its subject is eminently operatic: the true story of Nancy Randolph, a member of one of Colonial Virginia's proudest families. Randolph had a child out of wedlock, a more disgraceful thing in the 18th century than 200 years later.

The baby died and she and her presumed lover were tried for murder. They were acquitted in court but not in the malicious gossip of their contemporaries. She was rejected by her family and got a job teaching in Connecticut. But her reputation followed her: After a schoolgirl from Virginia spread the story, Randolph had to leave again. She became an employee of Gouverneur Morris, a wealthy diplomat and one of the principal authors of the U.S. Constitution.

After a year, they married. Morris's nephew Ogden, worried about losing his inheritance, got Nancy's brother and sister to write Morris a letter reviving the slanderous gossip. Morris did not believe the accusations and had a quarrel with Ogden, who threatened him with a pistol but was driven off when Nancy confronted him with a saber. Finally, Nancy put an end to the rumors by publishing the letter and her vigorous refutation.

Opera is an art that one learns by doing, and "Nancy" is Hull's first opera (for which he wrote both music and libretto). It stands up well when compared with the long-forgotten first operas of Verdi and Puccini. Still, it does need work, particularly in Act 1. It gets stronger as it goes along, however, and ends with vivid impact. The music is melodic and expressive but sometimes would benefit from more vigor.

Under the direction of John Edward Niles, the chief characters are well drawn. Vocally and dramatically, Michael Nansel had the strongest impact as Ogden Morris, a juicy villain's role. Ingrid Cowan was impressive as the other main villain, Nancy's sister Judith, and Ole Hass was his usual dependable self as her brother John.

The leading roles were well cast. Carmen Mason (Nancy) sang beautifully throughout; her characterization was rather passive up to her marriage with Morris, but that was rooted in the role. Robert Tudor was exactly right, vocally and dramatically, as Gouverneur Morris. The opera is not yet orchestrated, but Jonathan William Moyer provided sensitive accompaniment on the piano.

At the moment, "Nancy" is a work with great potential. With an orchestra, sets, costumes, a good stage director and some tightening and invigorating, it should realize that potential in later productions.