'Another Earth': Life on parallel planet

The concluding twist of "Another Earth" doesn't quite have the ironic stab of O. Henry, or the existential bogeyman quality of Rod Serling, or even the I-should-have-seen-it-coming cognitive whiplash of M. Night Shyamalan ("The Sixth Sense"). Like the rest of this hybrid, sci-fi indie drama, it's too understated for all that. But once the viewer stops scratching his or her head, and the mental mosaic of director Mike Cahill finally assembles itself, the only reasonable response is an audible gasp.

A twin to our own planet -- home to an existence that parallels our own -- has entered our sky. It's this mystery orb that Rhoda Williams (Brit Marling) is looking at, out her car window, after a party, when she runs a light, kills a pregnant mother and child, leaving the widower in a coma.

Rather than entering MIT, as she'd planned, Rhoda goes to prison, and four years later looks up the man whose life she ruined, promising composer John Burroughs (William Mapother). Burroughs is drowning his grief in liquor and pills and can use a housekeeper, which is how Rhoda presents herself. And it's as a generous, overqualified domestic that John sees her, as they gradually fall in love.

False identity between lovers is not a novel device, but "Another Earth," even without that other Earth, would have been an absorbing drama, thanks to the script by Cahill and Marling, and a convincing performance by the latter. The alternate world's existence, with its tantalizing promise of new beginnings and might-have-beens, is an inspired invention, as well as a metaphor that develops as the movie makes its way toward heartbreak, or exhilaration -- or possibly both, depending on how one sees that ending.