Imagine if all of a sudden things in space shifted slightly and we discovered another planet that was just like ours. How would we react? What would we do first? Who would be the first ones to travel there? Would we travel there?

All these questions and then some make up just part of the wickedly imaginative sci-fi romance 'Another Earth,' which is one of several films screening at the 2011 Sundance Film Festival that uses a low budget to blend genres while presenting very relatable relationship stories that are infused with a sci-fi twist. Thankfully, 'Another Earth' is one that pulls this off with great success -- an emotional roller-coaster ride that focuses on identity and questions how much we know about ourselves, as well as how much more we're willing to learn ... or forget.

Brit Marling, a sure-to-break-out-soon newcomer plays Rhoda, a brilliant girl obsessed with the stars who makes a stupid mistake while partying with some college friends one night and winds up driving home drunk. The night of the party also happens to be a historic day for all mankind as another planet just like ours is discovered just beyond the moon. As Rhoda leans out of her car window to focus in on the tiny blue dot of a planet, she crashes head on into a family (father, pregnant wife and toddler) traveling home. Everyone but the father is killed instantly, and Rhoda heads straight to prison.

The story picks up four years later with Rhoda out of prison and roaming around her small town like a zombie. Unable to find any sort of relief from the immense grief she's been experiencing for years, Rhoda decides to locate John (William Mapother), the father of the family she destroyed, in order to attempt some sort of an apology. But when she chickens out and makes up a lie about being part of a cleaning service, Rhoda suddenly finds herself thrust into John's messy, unhinged life -- all while the planet prepares to send its first group of people (one of which may be Rhoda) to what's now been deemed Earth 2 (take from that name what you will; we won't spoil it).

The film revolves heavily around Rhoda and her emotional quest to forgive herself while the Earth 2 subplot colors the background. Slowly we learn more about this other Earth, and those answers soon mix with our storyline forming one complex narrative executed extremely well by director Mike Cahill, who co-wrote the script with Marling. At times it does feel as if neither story is completely satisfying because they're both sort of fighting each other for screen time, but it's sort of up to the audience member to decide how much of each portion they require to feel satisfied, and Cahill certainly satisfied this one.

Not only does the filmmaker succeed with a unique, somewhat heartbreaking story, but he offers the sort of film that leaves you with a checklist full of questions about how much we're willing to commit to a life -- before we desperately desire a "do-over." Sure to be one of the year's most talked-about unique, fan-favorite sci-fi dramas (especially now that Fox Searchlight has acquired it for distribution), 'Another Earth' is worth seeing and digesting with an open mind, and probably a box of tissues.