Trip to the dark and bright sides of an icon

In "Gonzo," Alex Gibney uses footage of Hunter S. Thompson (above) and a gallery of people with inside information on the late journalist. (MAGNOLIA PICTURES)

The title of Alex Gibney's latest documentary, "Gonzo: The Life and Work of Dr. Hunter S. Thompson," neatly sums up its subject. It's an overview of Thompson's pioneering journalism and changing states of mind, serviceably presented as a fond, somewhat nostalgic glance in the rearview mirror of recent American history, clumsily connecting the travesties of the Nixon era to the travesties of the current one. Thompson - his brilliance, his self-destruction, and the ground he broke - is always at the center, but the film occasionally loses its focus.

As you might expect for a movie produced by the Vanity Fair editor and general éminence grise Graydon Carter, "Gonzo" is an all-access affair. Not only has Gibney rounded up tons of footage of Thompson (there's some choice stuff, for example, from an appearance on TV's "To Tell the Truth"), he has gained access to an impressive gallery of Thompson insiders: Jimmy Buffett, Tom Wolfe, Pat Buchanan, George McGovern, Jimmy Carter, Jann Wenner, Thompson's ex-wife Sondi Wright, his widow, Anita, and his son, Juan. They, and Johnny Depp's narration (intoning from Thompson's writings, at one point clutching a six-shooter while he reads), are all put to illustrative use, helping separate the complex explorer they knew from the weirdo persona he eventually cultivated.

The movie is also after bigger things. It wants to present Thompson as a visionary and an oracle. "Gonzo" opens with a reenactment of Thompson banging out one of his columns for ESPN.com. This particular one, written hours after Sept. 11, was full of unhappy predictions of conflicts to come. Gibney and his editor, Alison Ellwood, use the piece to build a montage demonstrating that his predictions have come true.

The past is the movie's strong suit. Thompson rode the wave of '60s indulgence (drugs and rock 'n' roll during the height of San Francisco's Haight-Ashbury period) that crashed in 1970s disillusionment. His violent, name-making time with the Hell's Angels in the mid-1960s eventually leads to his classic at-large work for Rolling Stone, where he chronicled a kind of American nightmare. A raw truth emerged from the reporting he did from the melees of the 1968 Democratic convention through the 1972 presidential election to his discovery of Jimmy Carter in 1974. And Gibney's movie delves into the entertaining paradoxes of Thompson's groundbreaking style. He merged reportage and a kind of louche fabulism to the point where his pieces resembled a funhouse-mirror version of reality: The truth was warped, but you could still make it out. To that end, his field adventures met their psychic X-ray and visual soul mate in Ralph Steadman's psychotic illustrations.

In capturing the social and moral cauldron the country had become, Thompson became a kind of disgusted activist, forgoing the journalist's credo of objectivity to show his readers what he thought was really going on. He embraced George McGovern during the '72 Democratic presidential primaries (he was covering the campaign) and enthusiastically trashed '68 nominee Hubert Humphrey and Ed Muskie, two of McGovern's rivals for the nomination in '72.

Somehow "Gonzo" never makes any great headway into Thompson's psyche. It may not be possible, the essence of who he was having been altered by decades of drugs and alcohol. The movie is always fascinating when it deepens into an examination of the era in which Thompson was working and how his attitude toward his profession really affected politics. Gary Hart, who was McGovern's campaign manager, discusses how Thompson's embellishments and dramatizations trivialized the tough work of running a campaign. And someone else mentions, in a similar vein, how Thompson's unorthodox - OK, unprofessional - comportment on the trail rankled the serious journalists in the press pool. Listening to them, I was struck by the fact that people say the same about bloggers today.

Gibney won an Oscar earlier this year for his superb military-torture documentary "Taxi to the Dark Side"; and in a move that might have amused Thompson, he's suing that movie's distributor for doing a bad job just in time for the release of his new movie. The current wars are an evident source of moral frustration and creative inspiration for him. But where Gibney's outrage in "Taxi" had the terrible, exhilarating chill of a well-told ghost story, events in "Gonzo" are disorganized in a way that leaves us with only a vague sense of the trajectory of Thompson's professional decline.

It's worth noting that the film's gravest shortcoming is its soundtrack. Gibney loads the film with hits from the 1960s and 1970s in the least imaginative, most hand-holding manner, the way Nora Ephron often does with standards in her movies. The documentary doubles as a jukebox of banality. Thompson discusses his funeral preferences: "Spirit in the Sky." McGovern gets the nomination in '72: "You Sexy Thing." His soon-to-be-ex running mate, Thomas Eagleton, admits to having had shock therapy: "Going Out of My Head." These songs bring Gibney's film closer to "Sleepless in Seattle" than any film about Hunter S. Thompson ought to be.

Wesley Morris can be reached at wmorris@globe.com. For more on movies, go to boston.com/ae/movienation.