DAVID MITCHELL'S 2004 novel Cloud Atlas has long been considered unfilmable, and make no mistake: It still is. The new movie by the Wachowskis and Tom Tykwer is very much an adaptation, borrowing the basic outline of Mitchell's book to create something entirely its own.

The film juggles six characters with six distinct storylines, set in time periods ranging from the 1830s to a distant, post-apocalyptic future. The characters' lives are linked by the stories they leave behind: a 19th-century gentleman writes a journal that is read by a composer in the 1930s, the composer's symphony is unearthed by a journalist in the 1970s, and so on. These stories aren't told chronologically, but in tandem; time-hopping scenes are spliced together in an impressive sleight of editing that maintains tension within each vignette and the film as a whole. Moreover, each storyline has a distinct style, from the slick futurism of a story set in "Neo Seoul," where a sub-human class of clones is genetically engineered to do menial labor, to a smarmy '70s drama starring Halle Barry as a plucky young reporter.

Some appalling makeup jobs notwithstanding, part of the fun of Cloud Atlas is watching different actors play different roles in each story: Tom Hanks' roles include a murderous doctor and a gibberish-spouting tribesman; Ben Whishaw plays both a moody bisexual composer and an elderly woman. Actors are cast across race and gender, and it's worth sticking around for the credits to see how many crossover cameos you missed.

Given the audacity of its undertaking—and its nearly three-hour runtime—Cloud Atlas is remarkably cohesive. Some storylines resonate more than others, but they're all efficiently told: Each episode is distilled to a few key characters, a few crucial scenes. But while its pieces are impressively wrought, the only theme that clearly emerges from the film as a whole relates to the persistence of the human spirit through the ages. That's kind of a bullshitty theme, really—for all the energy and flair this adaptation possesses, it's so focused on pulling off the logistics of adapting Mitchell's novel that there isn't room for much depth.