Twyla Tharp Hitting `Ecstatic Heights'. Choreographer is giving American Ballet Theater three things every company can use, starting with profound talent

AMERICAN BALLET THEATER is celebrating what may be its most important acquisition in a decade with several gala performances of Twyla Tharp's choreography. Tharp has made a number of pieces for ABT, a New York-based company that tours nationally. But when she became a resident choreographer last summer she brought not only her capacity for inventing new ballets but a nucleus of her own dancers and a bagful of readymade works. By the end of ``In the Upper Room,'' the first ballet at the San Francisco Opera House, the audience was delirious, and the evening climbed to ecstatic heights with two new works, ``Quartet,'' to music of Terry Riley, and ``Everlast,'' a 40-minute story ballet/musical to music of Jerome Kern.

Tharp has three things every ballet company needs and few have: an immense and profound talent, audience appeal, and the ability to seize the imagination of dancers. She's given ABT three wonderful and entirely different ballets, and the ABT stalwarts and youngsters who worked on them looked as if they'd discovered dancing for the first time. I felt, in turn, as if I were discovering them for the first time.

After ``In the Upper Room,'' Tharp's 1986 piece where ballet dancers and modern dancers collide and eventually merge in Jennifer Tipton's luminous fog banks, to music by Philip Glass, ``Quartet'' seemed like a trip in some pure, high-altitude desert. Clear and dry though it is, this piece for four of ABT's top classicists is far from simple. The interesting score for string quartet is like a fandango, insistently repeating a four-note descending line with variations, in a minor key. The music suggests a perfectly calm and predictable continuum overlaid with excitements of a darker shade. Tharp's take on it is geometric, virtuosic, and gripping.

The dancers, Cynthia Gregory, Cynthia Harvey, Ricardo Bustamante, and Guillaume Graffin, are dressed in Santo Loquasto's unisex black shorts and flowing white shirts with the sleeves rolled up. They move in stately lines and diagonal crossings, trading partners smoothly, spinning, dipping, twisting, and leaping with no apparent transitions between steps. They hardly seem to discriminate between being on the ground, in the air, or facing two directions at once, between absolute stillness and explosive speed.

They take fleeting Spanish-dance attitudes, as if subliminally touched by something in the music, but the dance otherwise has no reference to anything but dancing. Across the unbroken flow of it streaks a pas de deux - Gregory and Bustamante - in supported poses and lifts and minuscule solos; then Harvey and Graffin in another. After maybe 15 minutes, the four of them skid to a collective pose, and the music cuts off abruptly. The dance seems suspended and ready to go on to another variation, but instead the curtain falls.

``Everlast (A Gypsy Run-Through)'' is, among other things, a mini-musical comedy complete with everything but words. Tharp throws together several ballet and Hollywood stories and scrambles them ingeniously into a madcap romance set in the Palace Theater, 1919.

With gossip-column headlines that light up overhead to introduce the main characters (``Mrs. Hariman Loses Fortune''), the exposition is quickly accomplished. An ambitious mama (Georgina Parkinson) arranges the engagement of her flapper daughter (Susan Jaffe) to a famous but dumb prize fighter (Kevin O'Day). While the flapper dances with the five or six boyfriends she has no intention of relinquishing, the Champ dallies behind the potted palms with his Biggest Fan (Anne Adair), the Harimans' maid. Two Busy Bodies (Shelley Washington and Kathleen Moore) are scandalized by this, but later fix it so that the proper lovers get together for the happy ending. Before this can happen, the Fan dresses up as a boy and becomes the Champ's sparring partner, precipitating additional plot complications and mistaken-identity jokes. (Richard Colton is a cigar-chomping Trainer.)

There are party scenes and calisthenics, with a dance chorus of boys and girls in Edwardian clothes; important props like bouquets and hats - it was a derby that symbolized power and sex appeal in Tharp's ``Push Comes to Shove'' for ABT and its superstar artistic director Mikhail Baryshnikov. An onstage trio (Judy Blazer, Jason Graae, Molly Wasserman) belt out the 16 songs, accompanied by pianist Michael Dansicker and a pit orchestra under Jack Everly's direction. For no good reason it takes place backstage in a theater, with painted locales on panels that fly in and out. Santo Loquasto designed the sets and costumes. Jennifer Tipton did the lighting, William Brohn the orchestrations, and James Jones the scenario.

The whole thing is witty, fast, and absolutely unsentimental. What I think is so original about Tharp's send-up of plots, characters, and situations is how they all get transformed into something you didn't expect at the very moment you start to recognize them. I didn't always know what was happening, and I liked it that way. But I look forward to the performances in New York later this spring, when it'll be even more readable and more fun.

The piece ends with a big Broadway chorus line and a preposterous resolution of everyone's troubles in the last four bars. The audience was on its feet cheering before the curtain hit the floor.