BILL W. He founded AA. What've YOU done lately?

BILL W.—no last name needed—is familiar to any kid dragged to a church basement on a Friday night and told to quietly eat butter cookies while grownups take turns talking about how their obsession with alcohol repeatedly, unceasingly, keeps ruining their lives.

Bill's the long-dead co-founder of Alcoholics Anonymous, and he's revered as something close to a personal, tangible messiah among the hard cases who cling for dear life to his books, his "higher power" mantra, and his now-ubiquitous 12-step program. At a time when alcoholism either led to jail or the asylum, Bill W. offered a way out.

But behind the myth sits a simple, inescapable fact about the man, born more than a century ago as Bill Wilson: He was just another alcoholic.

And that's the singular—and perhaps most powerful—message that oozes from Bill W., an occasionally slow-moving documentary probing Wilson's life. If not for his failure, depression, and need for chemical relief that lingered long after he swore off liquor (Bill W. spent years experimenting with LSD and, later, vitamins), the salvation of so many others could never have followed.

True to the confessional style of the AA movement he helped seed in the late 1930s, much of Wilson's story is told in his own voice. He's joined by historians and associates, and by modern alcoholics, their faces cloaked in shadows.

Dealing with an ersatz god in a documentary can be touchy; how much truth does a director dare reveal? But directors Dan Carracino and Kevin Hanlon don't sugarcoat. We see Wilson in his final years, thinking of leaving his long-suffering wife for a younger woman, drained of his spirituality by a movement that's placed him on pedestal. And, then, we learn something more. What did Bill W. want most in the world on his deathbed? Whiskey, precious whiskey. Because, after all, he was just another alcoholic.