Blending science fiction and Sundance emo, Another Earth is a fascinatingly bizarre movie with a ludicrous premise. The deeper you get into this debut film from director Mike Cahill, the more you have to either go with it or risk losing your mind in the black hole of improbability that defines his new-age feature.

Co-written by and starring Brit Marling, Another Earth opens with precocious 17-year-old Rhoda Williams (Marling) driving home after a night of celebratory drinking. Distracted by a radio report of a newly discovered planet, Rhoda hits a car containing a Yale music professor and his family, with devastating results. In a split second, college acceptance to M.I.T. and a promising future as a scientist go out the window.

After four years in prison, a hopeless, despondent Rhoda moves back home with her family, takes a job as a high school janitor, and prepares to plod through a joyless, regret-laden life. Rhoda’s only glimmer of hope is the growing prominence of Earth 2, the planet spotted in the sky four years ago that has since become an idée fixe, especially as it moves closer to the people of Earth, filling the sky like a landing Spielberg spaceship. In what sounds like a stunt staged by Virgin Airways exec Richard Branson, Rhoda dreams of winning a contest that will allow our earthlings to travel to Earth 2.

The reason for that wish is clear. For Rhoda, the beckoning parallel planet offers hope of escape from the problems that consume her on Chez Earth. A slightly hokey metaphor for fate and destiny, Earth 2 is an exact mirror of the people and events on our Earth, where, perhaps, your duplicate could have made different choices and lived a happier life.

Consumed by guilt over the accident, Rhoda decides to reach out to the man whose life she destroyed in that accident four years ago. But standing outside his front door, her resolve breaks down. Trapped, she fakes a story about being a house cleaner, and in an act of Catholic penance, she begins to visit John Burroughs (William Mapother) weekly to clean his house and adjust his equally off-track, tragedy-pocked life of drinking too much and downing pharmaceuticals like M&Ms.

In this story about grief, loss, and — yes, I said it — second chances, some of the scenes, meant to be poetic, come across as borderline ridiculous. Nowhere is this truer in a scene where former composer John rekindles his love for music in a deserted concert hall by performing on a wood shop tool. The music is meant to suggest the eerie Theremin-like song of the cosmos. But like much of Another Earth, the scene feels goofily melodramatic, something more befitting a teenage John Cusack hoisting a boom box in Say Anything.

So it’s easy to feel two ways about Another Earth. On one hand, the film is laced with improbabilities and absurdly grandiose emotion. There are many hallmarks of young writers rushing so anxiously to tell their story that they don’t think we’ll notice the non-sequiturs and head-scratchers that pock the plot like Swiss cheese. And on the other hand, director Cahill has created a dreamy, impressionistic vision of an Earth that feels as alien as Venus. It’s certainly part of Cahill and Marling’s point: For Rhoda and John, the trauma they live with every day is a kind of sleepwalking detachment from the reality close at hand.

With its interplay of depressing steel-gray skies and the bright blue horizon promised by a view of Earth 2 in the distance, Another Earth is drenched in atmosphere. And its two appealing stars, especially the intelligent, ethereal Marling, hold the film together even as some of its more preposterous moments make Scientology look grounded.

Another plus: For its backstory alone, Another Earth is inspiration. Talk about parallel lives. In one, Georgetown grad Marling takes a job in finance at Goldman Sachs. In another, she leaves the promise of a gigantic paycheck at Sachs to pursue acting in Los Angeles, doesn’t like the cheesy parts she is offered, and decides to write something herself, with the help of Georgetown pal Cahill. I like the second premise much better.