THEY START PLAYING, ALMOST teasingly, outside. From the moment the UMO Ensemble enters through the huge hangar doors at Sand Point Naval Base--as a scrappy, musical band of survivors--I had the belief that these talented people would display an imagination expansive enough to match the 40,000-square-foot space. I spent the rest of the evening falling in and out of confidence with Millennium Circus (especially as its big treats are injudiciously saved for later), though UMO's new show is undoubtedly something to behold. The players actually take stunning flights across the ceiling, but somehow, I kept waiting for the piece to really take off.

Matthew Skenendore's set creates a vividly perilous world. The staging areas are filled with parapets, torches, clocks, mysterious Road Warrior-type machinery, and desktop towers. Light bulbs dangle from the ceiling. The UMO troupe--Martha Enson, Esther Edelman, David Godsey, Kevin Joyce, Janet McAlpin, Bradley McDevitt, and guest artist Jennifer Cohen--negotiate this new land nimbly, climbing over each other or zipping around on futuristic bicycles as they navigate us around their universe.

Sometimes the space swallows them. The night I saw the show there were still sound gaffes that had the audio equipment cutting in and out, rendering some dialogue incomprehensible in the unforgiving cavern. At other times, though, the production makes potent use of the absence of sound, employing the remnants of voices or lingering strands of music to fine effect. If anything, the biggest problem may be that the players have too much with which to occupy themselves, and when they get distracted, so do we.

Ensemble member Godsey, who conceived and wrote this show with input from his co-players and Larry Pisoni, envisions a microcosm of promise and disorder, then links it to our world's mounting Y2K tensions. The freeform show playfully mocks our society's pathetic assumptions about order (Joyce plays a neurotic consumed by business-speak: "I do not think--I respond"), and sends observations about pre-millennial selfishness tiptoeing into the recesses of our minds. Embarking on your way from one playing space to another, you hear loopy Luz (Martha Enson), as a parting thought, calling after you. "If you have everything," she wants to know, befuddled, "then what do you gain?" The text, with its words of encouragement and affirmation, sometimes verges on the preciousness of some psychedelic Mister Rogers' Neighborhood, but it's coming from an honest place, with the same plaintive yet hopeful heart that fueled UMO member Kevin Joyce's remarkable solo piece, A Pale and Lovely Place. Redemption, in this century or the next, comes from an understanding of our responsibility to each other: "After all the hoopla, you're still gonna have to face the neighbors."

Unfortunately, while the surface of this theatrical landscape is strikingly conceived, its core is not. Too often the piece resembles the chaos it's exploring. Millennium Circus was presented as a work-in-progress last year, and is obviously still feeling its way around its subtext. The scattershot approach to staging and the hectic fumblings of the cast are intentional, surely, but they don't always reap any artistic rewards. Godsey, in some lovely writer's notes in the program, quotes Isadora Duncan perhaps a bit defensively: "If I could tell you what it meant, there would be no point in dancing it." That's a nice sentiment, and I didn't expect to understand everything, but I did want the feeling that the piece itself, as a living creation, knows what it's doing, that somewhere within its depths (perhaps foreign to our consciousness) the piece is operating on its own obscure sense of logic. The show never quite comes to that full-bodied life, and I never quite believed the troupe had that much more of a grasp on the deeper meaning of their work than the audience did.

Still, the physical production can be fairly astonishing in its particulars, and for most people that is understandably enough. I am not going to be the critic to send an audience away from an evening featuring a choreographed bungee dance, with the cast members bouncing like notes in some spectacular stanza, high above what would be an extremely punishing concrete. There is certainly something to be said for spectacle--it feels miserly to gripe after witnessing some of this show's wondrous fantasies--but even the most outrageous sights lose force without the strong tug of some underlying purpose. There is a gem of a show waiting inside the storm that is Millennium Circus, but most of what we get is the sound and fury.