In the years since the name was originally coined, it sounds as if most filmmakers involved in the so-called "mumblecore" movement have come to resent the term, believing that it's an almost derogatory way to lump together all indie movies into a singular category. They have a right to this opinion, but it does seem as if they are misunderstanding the term. What mumblecore signifies (for this writer, anyway) is a film favoring characters and relationships over plotting, eavesdropping peeks into naturalistic life over push-and-pull contrivances, usually set in a confined time frame of anywhere between a couple hours to up to a few weeks. Most of them are, indeed, shot for very little money, occasionally improvised, and feature a cast of relative unknowns—all the better to complete the illusion of real people in real day-to-day experiences. Recently, however, more recognizable actors have been popping up, first in 2010's "Cyrus" (starring John C. Reilly, Marissa Tomei and Jonah Hill) and then in 2012's "Jeff, Who Lives at Home" (with Jason Segel, Susan Sarandon and Ed Helms). Both of these aforementioned pictures were written and directed by Jay and Mark Duplass, and now, in "Your Sister's Sister," Mark is on the opposite side of the camera alongside Emily Blunt (2012's "The Five-Year Engagement") and Rosemarie DeWitt (2008's "Rachel Getting Married"). The writer-director? Another prominent member of the mumblecore sort-of genre, Lynn Shelton (2009's "Humpday").

One year after older brother Tom passed away, Jack (Mark Duplass) attends a memorial get-together for him. As he stands back from the crowd, listening to people make idealistic, hyperbolic speeches about him, Jack finally cannot hold his tongue any longer. The other guests might like to remember a selfless nice guy, but Jack remembers what a bully Tom once was, and saw firsthand how he changed his ways when he found out he could get his way more often by being nice. Jack makes it perfectly clear that he loved his sibling, but there's no use in placing him on a pedestal just because he's no longer around. An uncomfortable but honest opening scene that knows exactly how to clench the viewer's attention, "Your Sister's Sister" sets itself up as the story of a man struggling to finally accept his own brother's death. Writer-director Lynn Shelton has other plans, though, and while she garners three terrific performances from her leads, she does so while losing sight of her most promising narrative thread.

Sensing that her best friend needs time for himself, Iris (Emily Blunt) urges the unemployed Jack to go stay at her family's cozy island retreat off the coast of Seattle. Jack reluctantly obliges, but is surprised to learn when he arrives that Iris' older half-sister Hannah (Rosemarie DeWitt) is already there, nursing a recent break-up with her longtime girlfriend. Hannah doesn't know Jack very well outside of what Iris has told her, but she graciously invites him to stay. Too many shots of tequila later, Jack and Hannah have slept together. It's a little awkward the next morning, but made all the worse when Iris arrives unannounced. As it turns out, she is in love with Jack—she has been for a long time—and thinks it's time she come clean with him about her feelings.

As the twisted web in "Your Sister's Sister" mounts, the uncoddled, non-compromising turns from Mark Duplass, Emily Blunt and Rosemarie DeWitt remain true and sympathetic even in the face of some leap-like stretches. Hannah, especially, has made some very poor decisions that could jeopardize her relationship with Iris, who, in turn, may not be able to look at Jack the same way again. As all of this works itself out and Hannah reaches a catharsis about herself, the very point of Jack's trip is sidelined. There is a wordless scene set in a diner where he observes two little boys at another table and is poignantly reminded of what he once had and has now lost—not just by death, but adulthood in general—but that's pretty much where Jack's arc on the subject begins and ends. It's a disappointing case of misdirection, and might have given "Your Sister's Sister" the added weight it needed to be more than just a pleasant, well-acted semi-love triangle dramedy.