We expect Quantum Theatre to do the unusual, challenging and unexpected. But with "The Collected Works of Billy the Kid," it does so by presenting a theatrical adventure that isn't, in the usual sense, a play. As to just what it actually is, I'm still working on that.

		'The Collected Works of Billy the Kid' Where: Quantum Theatre at Garden Theater, 12 W. North Ave., North Side. When: Through July 1; Wed.-Fri. 8 p.m.; Sat. 5:30 and 9 p.m.; Sun. 7 p.m. Tickets: $25-$30; $15 students; 412-394-3353.

It's certainly fun. That's mainly because of the brilliant elements it assembles, including a poetic text, five distinctive performers and an evocative performing space that provides an interpretive context to help make some sense of it all.

Space first. For a theater company that always finds unconventional and/or barely imaginable places to perform, the oddest aspect of this one is that it's already a theater. Arriving for a Quantum show and finding yourself in a theater lobby is the ultimate surprise.

But this is a theater with a difference, the notorious Garden Theater on the North Side. The Garden's history as a renegade porno house testing the law and social tolerance is a perfect context for a play that riffs on a famous renegade who was both social pariah and idol. And since some of Billy the Kid's myth was built up on the silver screen, there's additional resonance in its being a movie house.

There's also the physical space itself, with its darkly reddish, peeling walls and musty smell of rot. It reminds me of the dusty grandeur of Brooklyn's Majestic Theatre, which the Brooklyn Academy of Music adopted 20 years ago for Peter Brook's epic, daylong "Mahabharata." That dilapidated movie palace was a potent metaphor for ancient India, seen through the long lens of theatrical invention. The more modest Garden recalls a more recent myth-making, that of the American West.

The audience sits not in the original seats, but on steep bleachers, the better to see. We are in the tawdry space but not exactly of it.

"Billy the Kid" quickly puts its cards on the table. An old parlor organ plays with that haunting movie-palace sound. Five actors confront us. An older man shoots a younger one -- Billy, no doubt. An old record player plays honky tonk. The actors change costume, returning to the myth-making world, then share the first of many shots of whiskey -- there are bottles on every surface. And the text begins with the first taste of the music of Michael Ondaatje's 1970 volume of poems, from which this is adapted.

Those are the basic elements -- music, attitude, alcohol, make-believe and poetry. Note that plot is instantly disposed of: Billy is shot, there's no suspense about it. Now what?

"What" is a staccato series of scenes all relating to the short, murderous career of William H. Bonney, a k a Billy the Kid. Occasionally they fall into what might be chronological order. But different actors seem to be Billy at different times, so the collage continually challenges us to see it as we will or, better yet, to savor the pieces separately, finding unity in our response, not in what will always be a story open to interpretation and retelling.

Most amusingly, given the setting in this postlapsarian Garden, the action begins with a striptease -- a double tease, since so little is revealed, even though Kristin Slaysman performs her titillating, dipsy dance with drunken good cheer.

She's the sexy young woman, most often playing Angela, one of Billy's girlfriends. Andrew Hachey is the young man with curly hair, most visually convincing as Billy. John Fitzgerald Jay is the roughneck who can be suave and eventually becomes Billy's nemesis, Pat Garrett. Rick Kemp is the older man, often with a ventriloquist's dummy which is also Billy -- I'd call Kemp the myth-maker. And Mikelle Johnson is the spiky-souled musical provocateur.

So by poem, song and many scenes, the 91-minute story is disjointedly told -- or at least explored or summoned, linear narrative not being the point. There is little detail about Billy's contested life. The show is set at the junction of ordinary life and myth, and you should react as you do to poetry, letting images accumulate.

There are scenes both sexy and domestic, violent and contemplative. Hammer blows in full view make effective gunshots. Props are everywhere and are used amusingly -- a bunch of noisy small machines help illustrate a bloodbath. There is also a bath involving male nudity and plenty of blood. And a make-believe "movie." And breathtaking passages of poetry -- I'd go back just to hear them again.

The design seems accidental, with its elements merely found, but of course it's very canny. I'm especially struck by C. Todd Brown's lighting. The master creator is director Dan Jemmett, who led the ensemble in its imaginative response to Ondaatje's book.

In one sense, it's a ritual. In a pause just before the story returns to the killing with which it began, the cast passes out shot glasses that turn out to contain (if you're of age) real whiskey. "Billy the Kid" is all make-believe, but it's real at its core. It just isn't "realistic." Both gritty and seductive in the flesh, it's really theater of the mind.