http://www.missingallen.com/

One of the best documentaries ever made.

Somewhere around the mid-way point, this fascinating film moves off the beaten path into a dark area of America, one criss-crossed with secret roads and sinister people. Allen has been missing for 4.5 years, and a fellow documentary film-maker goes to find him. By the time the search leads to the basement of an Oklahoma monastery, and the discovery of an abandoned once-beloved car, the viewer realizes there will be no happy ending to this story. We find that Allen has been drawn into a sinister and sad world of cult theorists, and more and more creepy elements are brought forth to be revealed. An abandoned cabin in the mountain of Colorado provides further links; the approach and search of the house are terrifying in a way that it shouldn't be...after all, it's only a house, right? But the connections made to the apparent crime force the viewer to see everything through the lens of worst-case scenarios. The only sticking point? Why didn't we get to see any of Allen's unfinished films that he had been working on in Oklahoma?