Friedrich von Flotow's "Martha," playing tonight and Monday at the Lyric Opera House in Baltimore, is a delightful little opera, poised charmingly on the brink of operetta. It is not likely to have a brighter production locally for the rest of this rapidly dwindling century.

The Baltimore Opera production is notable for creative imagination and inventive use of fresh talents. A witty new singing translation is used. So are surtitles, which enhance clarity and enjoyment.

One aria from "Martha," "Ach, so fromm," was recorded by Caruso in Italian under the title "M'appari." Another familiar number, "The Last Rose of Summer," is a sort of leitmotif in "Martha's" second half. But other numbers are equally good, including a maidservants' chorus, a baritone aria in praise of beer, and the great quintet with chorus that ends Act 2. Flotow's music has the solidity of Germany, where he was born, enriched with traces of the graceful Italian bel canto style and refined with the elegance of Paris, where he was trained.

In "Martha," Lady Harriet Durham, a courtier to the queen of England, and her friend Nancy seek excitement by disguising themselves as maidservants. Hired by a pair of young bachelor farmers, they rebel when they are put to work. But by then they have fallen in love with their employers, despite differences of social class. The opera is close to pure froth. But sometimes an episode of real feeling intrudes, all the more effectively because of its frivolous context.

Director and costume designer John Lehmeyer has updated the story from 1710 to 1926, exploiting opportunities for creative design of flapper dresses and antique bathing suits. A spinning wheel that horrifies Harriet and Nancy in Act 2 of traditional productions becomes a vintage washing machine (with a wooden tub and crank) and a hand-operated clothes wringer in this production. Beach balls and croquet mallets are well used in Mary Corsaro's imaginative choreography.

In the pit, the Baltimore Symphony Orchestra responds precisely to conductor George Manahan. The chorus is excellent, including several women who have a few solo lines. Fine performances are heard from tenor Glenn Siebert, baritone James Michael McGuire and bass-baritone Mark Watson.

But the two female leads make this production one of the year's highlights. As Harriet, Sheryl Woods shows the same comic talent and sparkling tone that Washington audiences have enjoyed in such productions as "The Telephone" and "Wiener Blut." Mezzo-soprano Emily Golden has just finished singing here as the secretary in Menotti's "The Consul," and she is equally extraordinary in the somewhat less demanding role of Nancy. Her voice is a glory, her stage presence and acting ability are dazzling. May we see her again in Washington soon.