To get maximum benefit from the latest offering of the Summer Opera Theatre, you must love the soprano voice.

The company is closing its 26th brief but colorful season with a double feature that goes for maximum contrast except in its soprano emphasis. The first half of the program, an adaptation of Mozart's "Der Schauspieldirektor" ("The Impresario"), sung and acted in English, is set in a Hollywood studio in 1930, at the dawn of talking pictures. After intermission, it is another world; Puccini's "Suor Angelica," sung in Italian with surtitles, takes the audience into a convent of cloistered nuns.

In "The Impresario," three sopranos are auditioning for the same role, trying to upstage one another and swapping vivid insults. In "Suor Angelica," the stage of Catholic University's Hartke Theatre is packed with white-robed women (including a few mezzo-sopranos as well as higher voices) but no males. Puccini was a notorious killer of his soprano heroines but he also gave them melodies as sweet as spun sugar. In "Suor Angelica" they are often choral melodies, but the title role is lavishly provided with music that is exquisite, expressive and sometimes heartbreaking.

At first, Puccini's cloistered world is as bright and lively as Mozart's Hollywood (those nuns have personalities and they play little games on one another), but the liveliness quickly turns to tragedy, or at least to sentimental melodrama, without losing any of its sweetness.

Mozart's music was written for a play that was popular in the 1780s but became old hat long ago. The music remains (naturally) as bright and fresh as it was at the premiere, so the usual practice today is to revise the spoken dialogue beyond recognition, letting it serve as a pretext for the music.

In F. Robert Lehmeyer's new adaptation, sopranos Jennifer Graf, Hilary Ryon and Jennifer Jellings are trying out for a role in a movie about Mozart, singing their arias in front of a hand-cranked camera with lots of backstage jokes and atmosphere.

The singing and acting are splendid, including the contributions of Jeremy Blossey and Brian Cali, the only male voices heard in the program.

Graf, Ryon and Jellings humbly join the large women's chorus that produces lovely sounds in "Suor Angelica," while Christine Kavanagh undergoes agony and ecstasy as a woman banished to a cloister by her aristocratic family after bearing a child out of wedlock. Among the striking supporting performances are those of Veronica Jager as the Abbess and Laura Zuiderveen as the haughty Princess, Angelica's vindictive aunt and the only villain in the program.

Kate Tamarkin's conducting, the distinctive sets of Christopher Ash and the stage direction by Leland P. Kimball III are all first-class.

There will be repeat performances Wednesday, Friday and Sunday.

Christine Kavanagh is sent to a cloister after bearing a child out of wedlock in Summer Opera Theatre's "Suor Angelica."