"Protean" is the word: with his insatiable hunger for trying new styles, Michael Winterbottom is one of the most exciting directors working today.

Every new film is an experiment in a different format: the quasi documentary "In This World," the historical drama "The Claim", the biopic and ecstasy ethnography "24 Hour Party People," the dystopian tragedy "Code 46," and his last film, the taboo-breaking celebration of youth, sex, and rock'n roll "9 Songs." Winterbottom's shape-shifting powers go a long way toward explaining his fascination with Laurence Sterne's remarkable 18th century novel "Tristram Shandy." The book consists of a fragmented, unreliable narrative that was post-modern long before post-modernism; there are black pages, long digressions, and other eccentricities. Long considered unfilmable, it's just the thing for Michael Winterbottom.

The straightforward plot of "The Life and Opinions of Tristram Shandy, Gentleman" is summed up quickly; it consists of the costumed buffoonery surrounding Tristram's birth, where his father Walter (Steve Coogan) makes polite conversation with Dr. Slop (Dylan Moran) while his wife (Keeley Hawes) screams during labor. Coogan as Tristram narrates a few digressions, and Walter's brother Toby (Rob Brydon) can't stop talking about the mysterious injury he suffered at a battle he is now recreating in the backyard. A questionable birthing device called a "forceps" is discussed and demonstrated, Groucho Marx is quoted, and young Tristram is circumcised by accident.

So far so good: most of that is in Sterne's book. But just when baby Tristram's head is about to emerge from his mother's womb, a director calls "cut" and we go meta: it's all a movie! On the set, Steve Coogan now plays Steve Coogan, a vain and insecure actor who engages in petty one-upmanship with Roy Brydon (Roy Brydon.) Coogan's girlfriend Jenny (Kelly MacDonald) is visiting the set with her baby, a reporter is after him with a dirty story, a production assistant (Naomie Harris) lusts for him. And there's more: Coogan has to crawl headfirst and naked into an oversized rubber womb, Gillian Anderson flies in to take a part at the last minute, and for the first time ever, the DVD extras are actually referred to in the movie itself. In the hands of Michael Winterbottom, the unfilmable po-mo novel about chaos and the impossibility to tell a story straight (as a helpful professor explains) has become a meta-film about the improbability of making a movie. It's a riot.