"Darwin's Nightmare" fully lives up to its chilling title, a cinema verite journey to the heart of darkness -- not, mind you, the heart of Africa, where it transpires, but to the murkiest reaches of human apathy and despair.

The documentary, which was made by Austrian filmmaker Hubert Sauper, examines a phenomenon that took root 40 years ago in Lake Victoria, in Tanzania, where as a "little scientific experiment," the Nile perch was introduced to the thriving aquatic ecosystem. In short order, the voracious fish ate everything in its path, including other fish and the lake's myriad plant species. Today, the Nile perch is Lake Victoria's only denizen and even now the species is cannibalizing itself.

It turns out that, for Sauper, the Nile perch is an apt metaphor for the First World and its rapacious exploitation of Africa's natural resources. "Darwin's Nightmare" makes it clear that the disaster isn't just environmental but economic, with Lake Victoria's towns being forced to become monocultures, where processing plants prepare hundreds of tons of fish a day for export to Europe. As Sauper informs viewers in one of the film's several intertitles, 2 million white people eat Nile perch every day. In a stinging irony, precisely that number of Tanzanians are starving, able only to consume the fish heads and maggot-infested carcasses.

With unblinking, often sickening deliberation, Sauper methodically connects the dots that begin as seemingly unrelated interviews with Russian and Ukrainian cargo pilots, teenage Tanzanian prostitutes, orphaned children living on the streets and the chief of a multinational corporation that bears a striking resemblance to ThreeBees from John le Carre's "The Constant Gardener." What gradually comes into focus is a terrifying, appalling, infuriating cycle of exploitation and corruption, with those pilots flying in weapons for Africa's myriad civil wars and flying out fish, leaving Tanzania impoverished and dying. (One observer notes that about 10 fishermen die a month, mostly from AIDS contracted from prostitutes, as well as the occasional crocodile attack.)

Sauper takes his time building his case, never inserting his own editorial voice but letting the Tanzanians, and occasionally a representative of the World Bank or European Union or United Nations or some other interchangeable part of Ineffective and Cynical Bureaucracy Writ Large, tell their own story. That story is one of constant, unalloyed grief, as the film's subjects, many of them children, fall victim to poverty, HIV, violence, greed and, the granddaddy of them all, indifference. (Even the plastic used in packaging the fish is implicated in this grievous matrix, as the kids are shown melting it down to sniff its narcotizing fumes.)

"Darwin's Nightmare" is many things, including an environmental cautionary tale, a critique of globalization and a portrait of a community, country and continent in deep crisis. But at its most profound level it's about the ways in which those of us on the receiving end of the supply chain routinely and unknowingly break faith with the most dispossessed and defenseless of the world. As one of the pilots says while recounting a past run in which he delivered tanks to Angola and brought back fruit from South Africa, that year African children got guns for Christmas, while European children got grapes.

Darwin's Nightmare (107 minutes, at Landmark's E Street Cinema) is not rated and contains disturbing images and adult themes.

"Darwin's Nightmare" draws devastating connections between Tanzania's fishing industry and starvation.