The writings of San Francisco playwright Peter Sinn Nachtrieb have always been a balance of the weird, the wondrous, the sensitive, and the cynical.  Nachtrieb likes to test artistic and cultural boundaries, daring his audience to surrender its expectations. He likes happy endings, but he also likes to subvert them and stand them on their heads.

In many ways ‘BOB: A Life in Five Acts’ is the quintessential Peter Sinn-Nachtrieb play. It combines all of the idiosyncrasies and struggles and odd artistic impulses we’ve come to expect from one of his stories. It’s crazy, and it’s complicated, but in a way, the message we are offered at the end is pretty simple—in, you know, a complex way.

In the currently running production of ‘BOB’ at Main Stage West, in Sebastopol, all of those wildly consorting contradictions are given the perfect playground on which to cavort and cartwheel and freely express themselves.

A bit of a dream project for director Sheri Lee Miller, ‘BOB’ is, in many ways, the perfect undertaking for her particular talents, requiring a high degree of artistic collaboration with her cast (one of Miller’s strong suits), while also demanding a strong artistic eye. Miller accomplishes all of this, bravely allowing the whole mechanism to feel as if it might go off the rails at any minute, but keeping it from doing so while brilliantly enhancing the sense of dangerous improvisation that is etched into the script.

Born in the restroom of a fast food restaurant in the American South, Bob — played from birth to old age by Mark Bradbury — is promptly abandoned by his mother, then unofficially adopted by a waitress at the restaurant. In the first of five eventful acts, Bob names himself, travels to country with his adopted mom, grows into adolescence, learns a pop-cultural encyclopedia of random historical and sociological facts, and sets his sights on the goal that will determine the course of his life: to somehow become a “great man.” As Bob grows up, essentially homeless, but driven by an optimism so pure it can be tasted in his kisses, he encounters and reencounters a bizarre parade of American stereotypes—good, bad, and otherwise.

Bob’s epic, cross-country, decade-hopping life story is supported and narrated by a chorus of actors played with jaw-dropping elasticity by Laura Levin, Gina Alvarado, Sam Coughlin and Nick Sholley, who all get chances to display their range, depth and comic ability. Frequently starting new stories with the line, “It is said, that . . .”— as in, “It is said that Bob was born on Valentine’s Day in the bathroom of a White Castle . . .”—the quartet of storytellers work wonders, together and apart. Roaming the pleasingly spare blank-canvass of a stage, they all change voices, postures and costumes to become the numerous outrageous characters—and a number of animals and inanimate objects as well—whom Bob encounters as he pursues his dream, suffers a broken heart, loses his way, and finds it again in the most unexpected of places.

Between each act, the chorus take turns performing a dance—each one an act of creative daring-do, exploring different themes such as hardship, hope, love, and luck.

There is, to say the least, a lot going on in ‘BOB,’ much of which rests on the shoulders of Bradbury, who perfectly embodies the character’s boyish openness. It is safe to say that Bradbury, along with the rest of the cast, all reveal talents in ‘BOB” that regular theater attendees have likely never seen them display on stage before.

Not everything in Nachtrieb’s ambitious script works. And though it happens rarely, some of the cast’s choices seem to treat certain revelations as punchlines rather than life-altering discoveries.

To some degree, that’s one of the most notable facets of a Peter Sinn Nachtrieb play: the absurd and the profound share the same moment so often, it’s difficult to know how to take them at times, and it’s up to the actors and director to decide whether to tip the glance in one direction or another. That, in many ways, is an extraordinary thing, because it gives the play enormous elasticity.

On the whole, Sheri Lee Miller’s production of ‘BOB,’ like its title character, is a thing of loose-limbed wonder and beauty. Extremely funny, achingly sweet, and disturbingly offbeat, this is a wacky, unforgettable journey across a surreal landscape, one that will likely leave you with plenty to ponder and respond to, long after Bob, and the people he touches along the way, finally discover what it really means to be great.

Bob: A Life in Five Acts, runs Thursday-Sunday through May 22 at Main Stage West. www.mainstagewest.com.