Agile, Mobile, Hostile: A Year with Andre Williams is one of those documentaries where it seems that the filmmakers approached their subject and started filming with one idea in mind, until real life intervened, and forced them into something much stranger and more uncomfortable and better than they'd originally planned. This is a double good thing in this case; the film that Agile, Mobile, Hostile started as was interesting, certainly, but not nearly deep enough to support a whole feature-length running time, while the film it became is a sometimes beautiful cinematic depiction of human fragility.

Andre Williams is a musician and songwriter whose particular genre cannot be nailed down; he has worked in R&B, in soul, in blues, and in some kind of angry variant of blues that feels equally indebted to punk and rap, though it predates either. He's a greatly influential figure whose name has been almost completely lost to history, despite penning the iconic "Shake Your Tail Feather" amongst other works. He was also a drug addict for many years, sinking so far into the pursuit of his habit that he ended up homeless and begging for money on the Randolph Street bridge in downtown Chicago.

I do not know what filmmakers Tricia Todd & Eric Matthies went looking for when they first decided to make a film about Williams; perhaps just the delight in interviewing a man whose life had been endlessly interesting, though full of suffering; perhaps it was the appeal of Williams himself, a foul-mouthed, unabashedly sexual old blues man who seems to lack any sort of filter between his brain and his mouth. Perhaps - though I doubt it - they expected their story to develop in the exact way it did.

During the year that Todd and Matthies followed him, Williams had something of a bottoming-out with his alcoholism, and thereupon dedicated himself to getting cleaned up, and back on his feet. And this is where Agile, Mobile, Hostile goes from being a simple documentary about a troubled man comme une autre, to being a fairly brilliant documentary about the human experience. Williams's path to recovery is not a movie-easy one; and by the end of the film, it's hard to say with any certainty that he has "succeeded". Which is exactly the point: we all want to better ourselves, but it's damnably hard to do that, and Williams is ultimately just one more lost soul whose life ought to have been much better than it was, given his achievements, but chance, prejudice and poor choices scuttled all that.

Though Agile, Mobile, Hostile is not an inspirational movie by design, it's somehow inspiring anyway. We are given what amounts to a vignette of a man's life at the moment he wrestles with his darker angels ans rises, if not triumphant or unscathed, at least alive and ready to keep fighting. It is a study of human endurance, centered on the figure of an unjustly forgotten bluesman; it is thus both a deliberate attempt to correct the historic record and a document of a man's attempt to reset his on personal history. It is a modest indie film, perhaps, but it is stuffed with humanity, and sympathy.

Agile, Mobile Hostile screens at the Chicago International Movies and Music Festival at St. Paul's Cultural Center, 2215 W North Ave. on Saturday, March 7, at 5:00 PM