James Gray's new film, "The Lost City of Z," is a story of obsession and wonder, told sensitively and imaginatively. It's a corrective in many ways to the offensive and exploitative films that have populated the adventure genre since its inauguration.

Based on David Grann's 2009 book, as well as the 2005 "New Yorker" story that inspired it, "The Lost City of Z" follows the life of British explorer Percy Fawcett. Fawcett rose to prominence for exploring the Amazon River in 1906 to draw more accurate maps of the borders between Bolivia, Brazil and Peru. In 1908 he ventured back to South America to find the source of Brazil's Rio Verde. Fawcett's exploits were widely publicized, both in Britain and the United States. Tales of his travels even inspired his friend Arthur Conan Doyle to write "The Lost World." But the most intriguing part of Fawcett's story, and his greatest folly, was his search for a mysterious city in the jungle, which he named Z.

In Gray's film, Fawcett (Charlie Hunnam) leaves for South America because his life holds little of interest to him. He's held back by his class: after taking down a stag, usually a great honor, Fawcett is prevented from eating with his superiors because, as one general puts it, "He's been rather unfortunate in his choice of ancestors." Fawcett imagines himself a war hero in the making, but instead he's ordered to map out the Bolivia/Brazil border, one of the few remaining areas of the world to be properly documented.

Fawcett leaves behind his wife Nina (played sensitively by Sienna Miller) and their young child. Percy and Nina have a radically egalitarian marriage (for the time), which the film only hints at. Miller avoids the clichés of the forgotten wife, instead presenting a woman who is Percy's intellectual match and who commands a great deal of respect. Still, the jungle calls to him. Accompanied by Henry Costin (Robert Pattinson, sporting a giant beard that renders him nearly unrecognizable), Fawcett leads his tiny expedition down the Amazon.

Cinematographer Darius Khondji renders the jungle exquisitely. He avoids the tradition of over-saturating the green colors, instead giving it a more naturalistic look. Without the wash of cool green colors, the oppressive heat of the sun is felt more forcefully. Fawcett and Costin run across many of the usual jungle irritants, like panthers, snakes and insects, but Gray avoids sensationalizing them. His portraits of the natives that Fawcett meets are nuanced: when they encounter a cannibalistic tribe, they only eat a man who has already died as a way to honor his spirit.

During his numerous trips to South America, Fawcett becomes obsessed with the titular city named Z. After discovering ancient pottery and tools, he is convinced that the natives originally had a city and a much more advanced civilization than their current tribes would suggest. This flies in the face of the establishment at the Royal Geographic Society, whose members view the natives as savages who are genetically incapable of the kind of innovation associated with White people. In fact, Fawcett was at least partially right: Machu Picchu was reintroduced to Americans and Europeans in 1911, proving that native South Americans had once had the kind of civilization Fawcett dreamed of.

Gray's choice to put Fawcett's views in conflict with the racist attitudes of the time is one of his masterstrokes. For years, films and books depicting early Twentieth Century Westerners have played up their racism as a corrective to past media that ignored it. But this also gave the dangerous impression that all Americans and Europeans were virulent racists. Many were, but by overgeneralizing that fact we risk the possibility of writing off those offensive views — if everyone was a racist, how can we judge anyone for holding those societally acceptable beliefs at the time? By having Fawcett believe that the Amazonian tribes are just as capable of having a civilization to rival Europe, Gray makes his critics at the Geographical Society even more offensive.

In a discussion after a screening at the ArcLight Hollywood, Gray also outlined his need to distance "The Lost City of Z" from other jungle films, particularly Werner Herzog's "Aguirre: The Wrath of God" and "Fitzcarraldo." In both films, racist men are driven crazy by the jungle and their interactions with native tribes. Although Gray admires both films and considers them anti-racist, he refused to make another film about a White man who goes mad in the jungle. There's nothing evil or supernatural that would make a man lose his grip on sanity in "The Lost City of Z." Rather, his downfall comes from his obsession with discovering the lost city.

Gray, who is often compared to American filmmakers who rose to prominence in the 1970s, shares that decade's penchant for slowly unfolding stories. His deliberate pacing may strike some as overly slow (especially those raised on nothing but comic book movies), but here it becomes engrossing. He's aided by an impressive cast. Hunnam is aloof as Fawcett, and it's easy to see why he spent so many years away from his family. Pattinson's role is as far from the brooding vampires of "Twilight" as one can get, and he provides a necessary dose of humor. In some ways, Miller's performance is the most impressive of the cast; she plays Nina as a woman of her own passions, who leads a fulfilling life, rather than the abandoned wife of a great man.

"The Lost City of Z" is perhaps the best film yet from a man who has made many excellent films. It's an absorbing tale of adventure and discovery, one that desperately needs to be told.

Watch the trailer below:

Reach Staff Reporter Brian Marks here.