To turn Shakespeare's "Much Ado About Nothing" into an opera, Hector Berlioz lovingly removed most of its vital organs. He cut plot in favor of subplot, axed enough characters to write a whole other opera, and removed all of the "ado" -- the tale of slandered chastity, feigned death and final forgiveness -- that inspired Shakespeare's title. The result, "Beatrice et Benedict," is a brisk little opera that, dramatically, may be running on one ventricle, but musically breathes the spirit of the original.

There were several moments at Wednesday's Kennedy Center performance of "Beatrice et Benedict" when the full force of Shakespearean comic epiphany shone through Berlioz's music. The performance, by the Washington Concert Opera, marks the debut of the group's new leader, the Australian conductor Antony Walker, and the return of the WCO to performance after almost a year's hiatus. Walker, appointed last March, replaces Stephen Crout, the founder of the group and its longtime leader.

In brief remarks to the audience, Walker noted that the weather has not been a genial collaborator with rehearsal and travel schedules, but the show must go on. Walker is affable, and affability is good strategy on a first date with a Washington audience.

Whatever the reason, bad weather, truncated rehearsal, or want of enough get-to-know-you time, the performance had an edge. This is not always a disadvantage. An established full-time group, from which one expects polish and cohesion, must deliver a burnished product; the WCO, which performs little-known or rarely heard works and only a few times a year, is more about high-risk juggling than perfecting the details. And that can be exciting.

The many things that went right Wednesday are proof that Walker has good taste, is sensible about tempo and dynamics, fluent at meshing soloists, orchestra and chorus, and can have fun with music in a way that is charismatic before a crowd. The overture captured the breathless syntax of Berlioz at his most manic, thoughts and half-thoughts tumbling forth in giddy succession. (Some composers have an excess of feeling or intellect; Berlioz had an excess of imagination). The end of the first act was finely balanced, a quiet sunset with the string sound fully fleshed even in twilight. Berlioz's offbeats, syncopations, rhythmic riddles and self-undermining melodic rhetoric were handled with confidence.

But then there was a dull tromp through the Act I Sicilienne, mysterious diction and thick textures from the chorus and aria accompaniments that were occasionally more gristly than tender. The foggy French of the chorus added to a distinct sense that while the whole performance was deftly presented technically, it wasn't Gallic. No garlic, no bubbles.

The soloists ranged from the good to the exemplary, especially Esther Heideman as Hero. Heideman's soprano has the pale hues and fair-weather clarity of Wedgwood, filled with colors that are light yet distinct, and she is capable of smooth, classical arches of sound. Hero, the character, is an innocent idiot; Heideman's performance hid the vacuity with pure charm.

Mezzo-soprano Theodora Hanslowe took the dramatically more substantial role of Beatrice. Hanslowe has a darker tone and lower depths than most Beatrices, and she was consequently a more brooding figure. In her Act II "Dieu! Que viens-je d'entendre" she clung to the tone, giving the piece earnestness and even a touch of morbidity. She was a sumptuous and husky Beatrice, more Marlene Dietrich than Kate Hepburn.

As Ursula, contralto Sally-Anne Russell (who doesn't sound much like a contralto) sang only a little, but consistently well; the light tone and easy production were a perfect balance to Heideman and Hanslowe in the Act 2 trio.

Only Donald Kaasch's Benedict requires mixed comment. Kaasch was an engaging Benedict, but the voice lacks the unforced reediness of a French tenor; high-lying passages brought out a bit of extra constriction in the sound, and that, in turn, produced unwanted emphasis and distortion of line.

The performance was presented without the vast tracts of Berlioz's dialogue, which was a relief. After translating Shakespeare's language into French, translating it back again for Anglophone audiences does unspeakable violence to any memory of the original. Instead, three actors (Holly Twyford, Ian Peakes and Rick Foucheux) presented excerpts from the original, somewhat altering the narrative sequence of the Berlioz. They were mostly reading from scripts, but they did it with spontaneity.