PARK CITY, Utah — Meet Dominic Noonan, gangland boss and protagonist of a new film called “A Very British Gangster.” Dom is a big guy with a big bald head; he has people beaten up, tortured, killed. When he and his thugs patrol their home turf of Manchester, England, in suits and ties, director Donal MacIntyre cues the music and the slow motion. Quentin Tarantino’s gangster flick “Reservoir Dogs” comes to mind at other points, too, notably in a pool-hall scene in which Dom sits at a table in mid-conversation and the camera orbits him as if he exerts his own gravitational pull.

It would all be pretty derivative, except “A Very British Gangster,” which opened at the Sundance Film Festival last weekend, is a documentary.

This fascinating film might also be the best action flick at Sundance, which this year finds the nonfiction categories packed with works that loot the vaults traditionally reserved for fiction. Mr. MacIntyre’s flamboyant bit of journalism offers a pulsing soundtrack, elaborate crane shots, and characters who talk (and act) as mean as they look. “Gangster” is Guy Ritchie meets “60 Minutes.”

Despite the genre-busting success of political films like “An Inconvenient Truth” and “Fahrenheit 9/11,” most of today’s nonfiction movies remain true to the self-effacing code of cinema verité, which dates from the mid-20th century: serious topics, handheld cameras, subjects filmed discreetly in their natural habitats. But in many of this year’s Sundance documentaries, the camera work is choreographed, or the story seems so bizarre it can’t be real, or both. The festival’s unofficial credo may well be: Truth is stranger than fiction — assuming you can tell the two apart.

Take “Chicago 10,” which set the tone when it opened the festival last Thursday. It’s a documentary, and it isn’t. Using transcripts from the notorious (and unfilmed) trial of the 1968 Democratic Convention protesters, director Brett Morgen created an animated re-enactment of the proceedings. The courtroom drama, which represents just part of the film, contrasts sharply with the archival footage, particularly when Nick Nolte’s rock-grinder voice chimes in.

What happens if a film relies entirely on creative dramatizations based on testimony? In the case of “Zoo,” an atmospheric exploration of zoophilia directed by Robinson Devor, the answer is something very bizarre. That, however, could have more to do with the subject than anything else.

Mr. Devor and his editor, Joe Shapiro, have pieced together a mosaic of the cinematographer Sean Kirby’s shadowy, hypnotic compositions and audio interviews of several men involved in an incident in rural Washington that gained brief notoriety in 2005: the death of a man as a result of having sex with a horse.

The pre-screening speculation surrounding “Zoo” was much the same mix of guffaws and prurient curiosity that erupted when the story originally made headlines.

This is exactly the attitude the filmmakers set out to dispel, but the film’s quixotic attempt to gain sympathy for one of mankind’s more peculiar sexual preferences is only mildly successful. The viewer craves more information, which “Zoo” stubbornly withholds. The trance-inducing nocturnal tableaus eventually get old, and Mr. Devor seems unconcerned that his narrators are not entirely honest about their habits. They insist, for example, that their equine encounters are all about tender loving care.

In “Zoo,” the interpretation — or presentation — of the facts takes priority over the facts themselves. Is this a betrayal of the genre? The same question applies to “Manda Bala,” Jason Kohn’s ambitious effort to sum up modern-day Brazil. The film bears a strong resemblance to the prismatic, detached documentaries of Errol Morris, under whose tutelage Mr. Kohn once worked. Like Mr. Morris’s films “The Thin Blue Line” and “Fast, Cheap & Out of Control,” Mr. Kohn’s is a polyhedron of separate narratives that together form a larger story. The footage, most of which is shot using Hollywood lighting, has an willfully artificial quality, with interviewees installed in assiduously curated spaces and, in many cases, speaking directly to the camera.

São Paolo is a city plagued by broad-daylight abductions and extremities of rich and poor, and “Manda Bala” (Portuguese for “Send a Bullet”), using a broad cast of characters, attempts to weave these phenomena together: Among them is a former kidnapping victim, a wanted kidnapper (who appears disguised in a ski mask), a cop who specializes in kidnapping cases, and, most interesting, a surgeon who specializes in reconstructing the ears kidnappers routinely cut off to secure ransom for their wealthy abductees.

“Manda Bala” has its share of charming moments, but it seems a bit too proud of its Rubik’s Cube complexity. It also suffers from Tarantino syndrome: The jazzy soundtrack drowns out a woman who lost an ear, and the carefully maintained color scheme of bright blue, green, and yellow seems downright insensitive alongside grainy footage of blindfolded kidnapping victims who fear for their lives.

Sundance is thick with tabloidready stories this year, including the fiction categories: “An American Crime,” which stars Catherine Keener, is loosely based on one of history’s most sordid police-blotter entries, and Adrienne Shelly’s sunny, well-received comedy “Waitress” was overshadowed by the murder of the director last fall.

But the most astounding B-movie tale of all is Dan Klores’s documentary “Crazy Love,” which tells a story so out there it must be seen to be believed. Burt Pugach began an extramarital affair with fellow New Yorker Linda Riss in 1957; when she got engaged to another man two years later, he hired goons to throw lye in her face. She adapted to life as a blind woman while he pined for her behind bars. Shortly after his release, she forgave him and they were married.

Aside from its splashy treatment of photos and newspaper headlines, “Crazy Love” is filmed like a traditional documentary — which makes sense, because it would never work as fiction. Despite all the delving into that other realm going on at this year’s festival, Mr. Klores’s film suggests the documentary will always have a home of its own.