What elevates the hiphop-and-diamonds doc Bling: A Planet Rock from novelty to essential viewing is danger—not potential-for-death danger, which is there, but potential-for-crash-and-burn-failure danger. Watching the film navigate the straits between exposé and exploitation is thrilling, its ultimate success more rewarding thanks to the ever-present possibility that it'll careen into self-parody.

Bling's conceit is brilliant. It's also fraught with logistical hurdles: transpose three diamond-encrusted hiphop stars from North America to Sierra Leone, capital of West Africa's diamond trade. The three men—Raekwon ("The Chef") of Wu-Tang Clan, rapper/jeweler-to-the-rap-world Paul Wall, and Puerto Rican reggaeton godfather Tego Calderon—embody narcissism and conspicuous consumption. First interviewed in their native land, the men explain their love for diamonds, the status they afford, the American dream they represent. Each beams with jewels, braggadocio, and, it must be said, ignorance—there's no way they can understand the extent of their impact on lives 10,000 miles away.

Neither can the viewer. When the film touches down in Africa, a story of transformation begins, as palpable as the poverty of the people of Sierra Leone. Writer-director Raquel Cepeda is unyielding, embargoing the entourages and luxuries the rappers are accustomed to, herding them from village to shelter to mine to school, demanding their participation. Which at times comes grudgingly—Raekwon refuses to get off the tour bus at a refugee camp for victims of amputations (which were doled out mercilessly by both rebels and government forces during Sierra Leone's 10-year civil war). The camera closes in, and his reticence turns poignant: "My heart is where it's supposed to be, for the people and all that, but I just don't wanna see them like that."

He eventually capitulates—and as the film progresses, so do each of his costars. Hiphop machismo is slowly replaced by stoic compassion. There's every opportunity for Bling to devolve into poverty porn or a backhanded exposé of hiphop's detachment from the real world, but what emerges instead is a portrait of reluctant understanding. Word is after the shoot Wall switched to an ethical diamond importer, Calderon stopped wearing diamonds altogether, and Wu-Tang are organizing a benefit tour of Africa.

New to DVD this week: Ratatouille (Walt Disney Video, $29.99), Pixar Short Films Collection (Walt Disney Video, $29.99), I Don't Want to Sleep Alone (Strand Releasing, $27.99).