One of the most visually and artistically exciting documentaries I've seen at this year's Sundance Film Festival -- or outside of Sundance in the past few years, frankly -- Protagonist is hard to define and easy to enjoy, seemingly scatter-shot but possessed by pure focus, full of invention and newness, but also firmly committed to sure-handed storytelling and classic tradition. Director Jessica Yu (In the Realms of the Unreal) was asked to create a documentary about the Greek dramatist Euripides; what she wound up doing was creating a documentary about the real-life journeys of four men that illustrate the themes of Euripides' ancient ideas about drama while speaking to the conflicts and challenges of our modern age. Protagonist is, at heart, a film about how story itself has a kind of DNA -- and how the ideas of storytelling replicate themselves, in that each of these subjects hears stories that help create who they are, and their stories reflect and reproduce those ideas in the stories they themselves tell.

A young man becomes obsessed with the TV show Kung Fu, which leads to his becoming a martial artist; later, Mark Saltzman realizes his pursuit of a myth has real-life consequences. Another boy is told he's powerless, weak, worthy of abuse; Joe Loya's desire to re-write that story leads him to embrace a life of crime as a bank robber. After a childhood of repression, a German youth becomes a committed social revolutionary; Hans-Joachim Klein later realizes he's become a lethal pawn for forces that want to exploit his principles. Finally, a boy in a fiercely Christian home tries to ignore his homosexual desires by proselytizing against the gay community as a man; eventually, Mark Pierpont has to try to reconcile his learned beliefs with his essential nature.

Yu's also painting a portrait of extreme ideas -- from the personal (Saltzman's martial arts mentor is a true jerk) to the political (Klein winds up as part of an armed group who kidnaps a group of OPEC ministers). And, just like in the stories of Euripides, certainty can lead to ruin. Yu uses puppetry to re-enact scenes from Euripides's plays -- and the lives of her subjects as well -- and the effect is striking and haunting. There's also animation in the film, but as immediately fascinating as those visual sequences are, there are subtler touches as well. We're shown Bible passages, bubblegum cards, old TV shows, flip-book animation, newsreel footage, home movies and doodles -- and realize that Yu's exploring all the ways we're surrounded by story, and all the ways we add to that invisible ocean of narrative we swim in, whether through personal remembrance or through public acts.

You could imagine Protagonist being navel-gazing and off-puttingly technical -- designed for an audience in horn-rimmed glasses and elbow-patch blazers -- but it's to Yu's credit that the film always feels universal and fresh and accessible, even as the subjects share their most personal stories or we're shown the moments and visions of ancient drama. Once upon a time, someone told each of us "Once upon a time ..."; Protagonist makes it clear through rich images and powerful personal sagas how every story we've heard has shaped the stories we are, and how the stories we tell live on in unexpected ways beyond their first telling.