PARK CITY. If the bursting-at-the-seams crowd at Sunday's (January 25) world premiere of "Going Clear: Scientology and the Prison of Belief" was any indication, the film festival world (and probably the subsequent HBO world) has been waiting impatiently for a cinematic pulling back of the curtain from the Church of Scientology. 

And when you absolutely, positively have to get informed on a subject in a reasonably smart, reasonably all-encompassing, reasonably passionate (without succumbing to sloppy outrage), narratively tight 120-minutes, it's hard to imagine a more reliable tour guide than director Alex Gibney

The absurdly prolific filmmaker can be counted on to deliver a comprehensive rendering of difficult issues and that's exactly what "Going Clear: Scientology and the Prison of Belief" is.

If you've read Lawrence Wright's book -- I have not -- or any of the recent string of tangential Scientology exposes -- including Wright's profile of Paul Haggis, which I did read -- only some of the things in "Going Clear" are likely to be new. In fact, the number of interview clips from various TV networks featuring the various key interviewees from the documentary makes it  obvious that most of the people who Gibney was able to talk to were the same people, mostly formerly high-ranking offices who ran afoul of David Miscavige, who have been on an anti-Scientology crusade for years. But Gibney is a master of synthesizing information and that's what he does here as well. 

[I find that I like Gibney more when he's exposing something of himself, as in something like "Catching Hell" or "The Armstrong Lie," but that mostly doesn't seem to be what he's in this for.]

With Haggis and "Chicago PD" star Jason Beghe, "Going Clear" leads with highest profile available ex-Scientologist celebrities. This sets a tone for the documentary, which caters to the public fascination with the rich and famous among Scientology's minuscule membership -- Only 50,000-ish, the doc estimates -- and to those aforementioned high profile Scientology defectors, including Mark Rathbun and Mike Rinder and several other departed Sea Org big-wigs.

"Going Clear: Scientology and the Prison of Belief" does the normal history of Scientology, including the standard (and not incorrect) evisceration of  L. Ron Hubbard as a hack science fiction author who lied about his war record, had an abusive first marriage, founded a religion in order to protect his money from the IRS and then still fled the country to avoid paying taxes. 

The documentary then begins the process of tearing into the absurdities of Scientology-as-faith, including its roots in the perennial bestseller "Dianetics" and the various oddities including auditing, going clear, engrams, The Bridge, Operating Thetan levels and the gloriously absurd grand mythology, including Xenu, volcanos and thetans. If "Going Clear" featured nothing but Paul Haggis' flummoxed reaction to the Scientology space opera, it would be worth it. It's the best thing Haggis has been involved with since "EZ Streets."

As harsh as "Going Clear" is toward Hubbard, it's far more hostile regarding Miscavige, The Church's public face and the owner of the terrifying title, "Chairman of the Board of Religious Technology Center." Miscavige was Hubbard's successor -- His announcement of Hubbard's death is truly warped -- and he has taken Scientology from a crazy-sounding money-making machine to a crazy-sounding money-making machine that is also frequently in the press amidst rumors of abuse, humiliation and even physical violence. 

Guess what? Miscavige didn't speak to Gibney.

Also remaining silence in the most predictable way possible are Tom Cruise and John Travolta, though Scientology's two biggest stars are the subject of much discussion.

Travolta actually is cut a bit of slack. He's seen as sympathetic toward his former handler Spanky Taylor, featured in the doc, and his interest in Scientology is linked to his troubled youth and to a remarkable string of professional success after joining The Church. It's telling that a rare on-set interview about Scientology in which Travolta celebrate's his religion's embrace of joy isn't close to the cultiest moment in the documentary. And I don't know if it's sympathy or if it was a rights issue, but Gibney doesn't even mention "Battlefield Earth."

Cruise, however, gets shredded into bits and pieces. The notorious black turtleneck video, which got ample play six or seven years ago, gets an extended airing and it remains the most intensely goof Cruise/Scientology footage. But Scientology's investment in ending Cruise's marriage to Nicole Kidman and then its desire to find him a new girlfriend, including a pact I hadn't heard of with a recent cable TV actress, sure don't look good. It also doesn't look good that Cruise has taken ample advantage of poorly paid Sea Org members to trick out his cars and planes among other services.

I wish Gibney was as interested in those exploited Scientology members as he is in the absent Cruise, Travolta and Miscavige. The mutually beneficial relationship Scientology has with its famous followers makes sense and I can't muster much sympathy for either side exploiting the other. But the vast majority of Scientologists aren't Tom Cruise or that guy from that sitcom. They're ordinary people who waste hundreds and thousands of dollars on seminars and audits and attempts to make very incremental pushes along The Bridge, maybe going clear, but never getting to one of those awesome OT levels where you learn the truth about The Wall of Fire and Xenu, much less to the even cooler OT levels where you can control people's thoughts or move objects with your mind. There is a Scientology base and they're not visible here, so there's no way of understanding what a casual Scientology thinks they're getting from the Church while they're being bled dry and not given access to cheap Sea Org labor.

Just because Haggis has written and talked about his departure from Scientology before, his feelings of betrayal are more honest and less contrived than any movie he's ever written. Haggis is also the only person in the documentary to bring up Scientology's hatred of homosexuality. 

And while Beghe has been outspoken about his Scientology experience for years, his animated and obscenity-filled stories are pretty spectacular.

And just as Rinder and Rathbun have been honest about their splits from Scientology and, mostly, Miscavige, the hypocrisy of their decades of public statements supporting the Church contrasted with their disappointment and confusion now is satisfying.

Even if you've heard about it before, there are chilling points made about Scientology throughout the documentary, from the threats of legal action against the IRS that led to its tax-free status to the way the Church has expanded real estate assets into the multi-billion dollar range even while becoming less and less convincing as a religion.

Maybe I wanted a little more fresh material from what was one of my most anticipated movies of Sundance, but even if you know nearly everything in "Going Clear: Scientology and the Prison of Belief," the presence of all of these talking heads, all of these statistics and all of these stories in one place is a service. 

And if you only know Scientology from the Hollywood Celebrity Center or a couple Tom Cruise jokes, prepare to be stunned, infuriated and, as you learn the details, highly amused by what Alex Gibney and Lawrence Wright have uncovered. 

Other Sundance 2015 Reviews:
"Kurt Cobain: Montage of Heck"
"Slow West"
"The Amina Profile"
"The Hunting Ground"
"The End of the Tour"
"A Walk in the Woods"
"Finders Keepers"
"How To Change The World"
"What Happened, Miss Simone?"

A long-time member of the TCA Board and a longer-time blogger of "American Idol," Dan Fienberg writes about TV, except for when he writes about movies or sometimes writes about the Red Sox. But never music. He would sound stupid talking about music.