They call it "Summer Madness." OK, it's just an advertising slogan that loosely ties together the three works currently in repertory for the San Francisco Opera's June season. But the title character of Donizetti's "Lucia di Lammermoor" offers more than enough insanity to go around, especially as portrayed by the dynamic French soprano Natalie Dessay.

Her belated company debut is bringing well-deserved cheers from critics and audiences _ including an estimated 23,000 people who watched a free simulcast beamed into AT&T Park, home of the San Francisco Giants, on Friday night.

Besides "Lucia," the company is performing "Das Rheingold," the opening work of Wagner's four-part "Ring" cycle, and Handel's rarely heard "Ariodante" in rotation through July 6.

Dessay, a pint-sized singing and acting phenomenon, has already triumphed in the role in Chicago and last season at New York's Metropolitan Opera. Originally she was to bring the Met production with her, but the company said technical problems made that impossible, so a Graham Vick production was imported from Florence, Italy. It's redolent of the Scottish Highlands, where the action is set, with tartans much on display and clumps of heather growing in the woods.

A first-rate Lucia always dominates the evening, and Dessay is no exception. Mentally fragile from the start, she melts down before our eyes as her ruthless brother forces her to abandon her sweetheart and make a politically advantageous marriage. Her mad scene is notable for limpid phrasing and crystalline high notes but most of all for long stretches of otherworldly calm, punctuated by an outburst of deranged laughter and one gut-wrenching scream. Dessay sings her own cadenza, echoing snatches of musical phrases played by a modern version of the glass harmonica.

As her brother Enrico, baritone Gabriele Viviani made his U.S. debut at Tuesday's premiere. Both he and fellow Italian Giuseppe Filianoti _ as her lover Edgardo _ have big voices that they employ with more regard for volume than vocal nuance. Filianoti, one of several promising young tenors currently on the world opera scene, has a lovely sound capable of ringing high notes, but when he pushes there are signs of strain that don't bode well for his future.

Conductor Jean-Yves Ossonce, also making his first U.S. appearance, had trouble with coordination between pit and stage in the opening scene and let the tempos drag throughout the first half. The pacing improved after the intermission.

No one goes mad in either of the other operas, but the greedy denizens of "Das Rheingold" are downright obsessive in pursuing the power contained in a magical golden ring. And the title character of "Ariodante" is tormented by a mistaken belief that his fiancee, Ginevra, has been unfaithful, while she is driven to despair by the false accusations.

"Das Rheingold," the first installment of director Francesca Zambello's witty American-themed "Ring" cycle, is being presented here two years after its premiere at the Washington National Opera. A few changes are apparent _ Erda, the earth goddess, no longer appears in Native American costume _ but Alberich the dwarf is still a gold-panning '49er, and Wotan and his fellow gods still resemble the idle socialites of "The Great Gatsby."

The chief difference is the higher level of performance, thanks to a world-class cast (many of them, appropriately, Americans) and superb conducting by music director Donald Runnicles. Rarely have the opening and closing measures, with their cruelly exposed horn passages, sounded so good.

With his booming tones and arresting stage presence, the bass-baritone Richard Paul Fink shows why he is the Alberich of choice everywhere from the Met to Berlin. Tenor Stefan Margita, a native of the Czech Republic, sings and acts superbly as Loge, the cynical demigod whose job is to get the gods out of trouble.

Singing Wotan for the first time, baritone Mark Delavan the vocal range and power that the role demands, though he hasn't yet developed a forceful characterization. It will be interesting to watch him take on the more grueling tests of the next two operas, "Die Walkuere" and "Siegfried."

Mezzo Jennifer Larmore, best known for her coloratura turns in Rossini and Handel, seems an unlikely choice as Fricka, Wotan's wife, but she sings the role well, despite some brittleness in the upper register. Mezzo Jill Grove is a commanding Erda and baritone Charles Taylor an uncommonly potent Donner.

Leave it to the most obscure of the three operas to provide the most surprising rewards.

The libretto says "Ariodante" is set, like "Lucia," in Scotland, but John Copley's spare production, first created for Dallas, seems to be taking place in Venice during the Renaissance, with sliding panels revealing occasional glimpses of a sunny waterway or fragments of statuary.

But locale matters little. What counts is Handel's genius for composing music that brings his characters to life with dazzling emotional complexity _ and having singers who can do it justice.

Susan Graham, the versatile American mezzo who triumphed here last summer in Gluck's "Iphigenie en Tauride," revels in Ariodante's two great contrasting arias _ "Scherza infida," an outpouring of despair, and "Dopo notte," a near-explosion of joy and relief.

Giving stalwart support as Ginevra is the still-formidable American soprano Ruth Ann Swenson, a local favorite since she made her debut here 25 years ago. The role of the villain, Polinesso, requires a contralto who can negotiate fearsome, rapid-fire coloratura, and Sonia Prina, a young Italian making her U.S. debut, proved equal to the challenge. Patrick Summers conducted a buoyant performance. Richard Croft, a fine American tenor, graced the relatively small role of Lurcanio, Ariodante's brother.

Amazing to think that this masterpiece, first performed in 1735, disappeared from view for more than two centuries, like most of Handel's operas, and wasn't heard in the United States until 1971.

San Francisco's pleasant tradition of performing opera in June, when many companies are shut down, stems from necessity. After its annual fall season at the War Memorial Opera House, the opera has to vacate so the San Francisco Ballet can perform in the winter and spring.

Local opera lovers apparently don't mind having their season broken up. The company says summer ticket sales are on track to do as well as in the fall.

Next June's repertory consists of Gershwin's "Porgy and Bess," Puccini's "Tosca," and Verdi's "La Traviata" _ the last with a Dessay-like superstar in the person of soprano Anna Netrebko, the Russian soprano who made her U.S. debut with the company back in 1995.

As Violetta she won't go mad, but she'll do the next best thing in operatic terms, dying a glamorously slow death from consumption.