"Who knows anything about Scott Walker?" asks David Bowie early on in 30 Century Man, a documentary about one of the true enigmas in pop music. As if to concede this point, director Stephen Kijak uses his movie less to examine the whys and hows of Walker's spooky art than to pay reverent tribute to his mythology—it's all shadowy headshots and monosyllabic responses.

This might be the price the director paid to gain the normally elusive crooner/sadist's full cooperation, which includes a rare on-camera interview. So while you'll leave the theater haunted by that voice (and coveting any records containing it you don't already own), you'll understand very little of what compelled the one-time '60s teen pin-up to lose himself in an ever-unraveling shroud of anti-pop.

Inquisitive viewers will be left with lots to inquire: What about those sunnier stretches in Walker's discography? A side career pimping the Bacharach/David songbook? An album of movie theme songs? They are swiftly brushed aside: Godlike genius doesn't do cash-ins, apparently. But on the upside, 30 Century Man is that rarest of rock tributes—it embarrasses neither its subject nor his fans.