SURELY THIS YEAR'S greatest movie bargain is "Another Earth," the sci-fi Sundance sensation made for about $1.35.

That's not counting ingenuity and imagination - unpriced commodities this movie has in surplus.

"Another Earth" opens with a teen (Brit Marling) on her way to MIT and on her way home from a high-school graduation party, seconds before her life changes forever.

She is probably drunk, yes, but she's also distracted - gazing into the night sky at the duplicate Earth that has recently appeared in the heavens, to the consternation and amazement of scientists and astronomers.

And at least one teen motorist. There's an accident; mere carelessness isn't the cause. It's the young woman's curiosity, her very nature, introducing ideas of fate and destiny that "Another Earth" takes up later on.

Fast forward several years - the woman is released from prison. She's defeated and depressed, but two things animate her: her ongoing curiosity about what scientists are calling Earth 2, still co-orbiting the sun, and a desire to contact one of the accident victims (William Mapother).

There's a strong scene of Marling's character approaching the man with the intent of offering some apology, then, at the moment of truth, realizing how self-serving this action really is.

She loses her nerve, stumbles into a cover story about belonging to a maid service, and ends up cleaning the man's house, leading to a truth-muffled relationship tinged with suspense, tenderness and, although the movie does not intend it, a bit of horror.

All the while, the other Earth hangs in the air, as do questions related to its implications. If there is a duplicate Earth, are there duplicate people? The girl wonders - is there another me? Has she made the same mistakes, suffered the same misfortune?

There are subplots in "Another Earth" about communication with Earth 2, a possible mission to Earth 2, but this is not a "contact" movie.

It stays on the "original" Earth, and leaves the mysteries of the duplicate planet unexplored. "Another Earth" has been ripped for this restraint. I don't know why. This is not the movie in which Vince Vaughn and Owen Wilson go to Earth 2 and date each other's duplicate girlfriends, and it never pretends to be.

"Another Earth" wants the implications of Earth 2 to be left to the imagination. Even the movie's final image - a boffo one, I'd say - raises as many questions as it answers.