Current indie poster boy Joseph Gordon-Levitt plays Bobby Thompson, and Lynn Collins (X-Men Origins: Wolverine) is his girlfriend Kate Montero. The couple has two prospects for the upcoming July 4 holiday: they could have dinner together in Chinatown, or they could attend a family barbeque at the home of Kate's family. They do not know which to choose. The movie then splits off into sections - one labeled GREEN and the other YELLOW - that show what happens (or would happen) with each choice.

In the YELLOW section, Bobby finds a cell phone in a cab on the way to Chinatown. He calls some of the numbers in its address book, trying to identify the owner. It turns out that the cell phone contains some very important information that certain parties are willing to kill for. When Bobby and Kate try to turn it in to a local police station, they are met with bureaucratic resistance. Their backup plan - decided on a we-don't-quite-understand-what-we're-dealing-with whim - is to try to negotiate a deal where they will deliver the phone to either the owner or a rival, depending on who offers the most money. It doesn't take long for them to realize that they're in way over their heads and may get killed over what began as an attempt to do a good deed.

The GREEN section finds them doing a good deed as well - in this case, trying to find the owner of a lost dog. They haul the pooch with them to Kate's family barbeque where her parents beg her to talk younger sister Sophie (Juno's Olivia Thirlby) out of her Broadway aspirations. But there's a more pressing issue: Kate is pregnant, hasn't told her family, and doesn't know whether to continue the pregnancy or terminate it. Bobby doesn't know either, but also doesn't know what Kate wants him to say.

In both halves of Uncertainty, the characters are placed in situations that they don't know how to get themselves out of. The film isn't so much about what they do as about exploring how they try to figure it out. While a thriller and a domestic drama would not automatically seem to fit well together, Siegel and McGehee make it work by drawing parallels. In other words, some decisions really are life and death, and others just really feel like they are. Or, going even further, the decision about Kate's pregnancy really is a matter of life or death for the unborn baby. The directors are interested in exploring how people make complicated decisions where there is no clear-cut path, and these two halves effectively allow them to do so.

Watching Uncertainty is quite an experience. Either half would work as a stand-alone movie; the thriller half is tense and exciting, and the domestic drama half is equally compelling. Nevertheless, seeing the halves put together sells the theme more effectively. You can see how Kate has decision-making skills in situations where Bobby does not, and vice versa. You also notice how the decision-making process works with these two. At times, they almost talk themselves into courses of action that neither of them would take individually. Watching how they interact and try to figure things out in very different circumstances makes this a unique character study.

Despite dual storylines, we never get lost, thanks to the use of the color scheme. Predictably, the color yellow pops up frequently in the YELLOW section (Bobby and Kate wear yellow clothes, for instance), and green pops up prominently in the GREEN section. But credit must also go to Joseph Gordon-Levitt and Lynn Collins, who guide us through both halves. It is a testament to their abilities that we know we're watching the same characters in both plot threads. The Bobby and Kate we see in YELLOW are the same people we see in GREEN, even though the dilemmas are different, as are their responses.

Uncertainty is beautifully made, and I was hooked the entire time. It's worth saying that viewers who like certainty may have problems with the ending, which intentionally befits the film's title. Emotionally speaking, though, the ending feels totally appropriate. Just to reiterate, Uncertainty is available via IFC on Demand, so if your cable company offers this service (and many do), here's your chance to catch a tiny little piece of awesomeness.

( 1/2 out of four)

Uncertainty is unrated R but has sexual content and some violence. The running time is 1 hour and 46 minutes.