The summer night ultimately smiles on "A Little Night Music," authenticating it with comic sadness and melancholy appropriate to lovers who have too long been foolish by moonlight.

The Hawaii Opera Theatre production of Stephen Sondheim's Broadway operetta has the right look and tone. Unfortunately, it also creates a numbingly long and static first act to introduce and intertwine its characters.

The shorter second act fares much better, allowing the cast of upper-crust Scandinavians to play out their romantic shenanigans during a weekend in the country. The second act also contains the show's best songs — Sondheim's most familiar piece, "Send in the Clowns," and the welcomed robust and red-blooded "The Miller's Son."

Based on the Ingmar Bergman film "Smiles of a Summer Night," the waltz-themed score is densely melodic, incorporating a reappearing quintet to comment on the action, quartets and solos that require good voices. The HOT production directed by Henry Akina and Timothy Shaindlin meets this requirement with a professional cast that delivers both the music and the subtle comedy.

Diane Alexander is competent and lovely in the central role of actress Desiree Armfeldt, deftly juggling two jealous suitors and delivering her "Send In the Clowns" solo with all notes and nuances clearly intact. Jake Gardner is comfortable and relaxed as her old beau Fredrik Egerman, tolerating a serious young son and a skittish young wife and building a solid character base with the show's first solo "Now."

Supporting roles are excellently cast, with Derek Taylor as lovesick seminarian, Audrey Elizabeth Luna as virgin wife, Leslie Tennent as dueling suitor and Jill Gardner as ignored wife. Rosalind Elias is a wealthy dowager and Kristin Stone the young daughter. As a lusty housemaid, Mary Chesnut Hicks injects adrenaline late in the play with "The Miller's Son," counteracting the inbred emotions of the major characters.

Peter Dean Beck's stage set is subtly edited, using three skeletonized inner prosceniums, one of which moves to frame new scenes. Proscenium boxes, a row of visible footlights, and carefully chosen props add period details to a setting that is otherwise starkly modern.

Beck also builds an acting runway that encircles the orchestra, adding to the presentational style and bringing the soloists down front to interact with the audience.

However, lovely music and pretty stage pictures don't rescue Act 1 from itself.

The book by Hugh Wheeler ponderously introduces characters from three separate households, the Liebeslieder Quintet floats in and out like a Greek chorus incongruously transported into Victorian Europe, and Sondheim's melodies begin to weigh themselves down.

Despite the coy humor, just about everything and everyone is taken much too seriously. The act finally closes with "A Weekend in the Country" promising relief to an overmannered society.

"A Little Night Music" has been called a musical for adults. But this production often crosses the line from maturity into stuffiness.

Joseph T. Rozmiarek has reviewed theater performances in Hawai'i since 1973.