Early in the film, Jack (Duplass) arrives at a rural cabin belonging to the family of his best friend Iris (Blunt), wanting a few solitary days there to get his head together. A year has passed since the death of his brother, and as evidenced from the awkward scene he makes at a memorial gathering on the anniversary, he still hasn't processed his grief. But when he arrives, Iris's sister Hannah (DeWitt) is there, dealing with a loss of her own. The two near-strangers drown their sorrows in a bottle of tequila, and end up in bed together—which becomes extremely awkward when Iris shows up unexpectedly the next day, initiating the revelation of a whole slew of secrets among the trio.
Before any of that begins though, there is a scene in which Jack looks through the window and sees Hannah inside, which is a surprise since he thought he had the place to himself. As he considers how best to proceed, he lingers just a little too long, transfixed by this sudden glimpse at her unguarded private moments.
The film itself is much like that moment of Jack looking in on Hannah through the window—only we're Jack, witness to private actions and exchanges that often seem too real to be in the movies. The characters' rambling conversations interlock and bounce off one another reactively in ways that written scripts have difficulty replicating.
Shelton follows in a long tradition of directors who have attempted to eliminate the inherent artificiality of cinema by embracing the unexpected. John Cassavetes's films were scripted, but he let his actors move and interact as the scene inspired them. With the actors dictating camera movements rather than the other way around, there was an air of documentary realism in his films that was heightened by the raw-nerve emotions of his storytelling.
The British director Mike Leigh also famously develops his scripts during improvisations that take place in lengthy rehearsals, allowing the actors to gradually build the script. Leigh's films are the best of both worlds in that sense: They bear the spontaneity of improvisations as well as the careful craft of words that have been labored over. His 1993 masterpiece Naked seems like it's unfolding in front of you fresh and in the moment, no matter how many times you've seen it, yet David Thewlis's Johnny is as quotable as anyone Tarantino has ever dreamed up.
The more recent antecedents for Shelton's style are the oft-improvised film of the indie mumblecore movement of the '00s. But she, like the Duplass brothers (of whom this film's Mark Duplass is one half), is quickly shedding any ties to that loosely defined movement as their filmmaking becomes more elegant and assured. Mumblecore's shoot-from-the-hip aesthetic often made its films ramshackle and aesthetically uneven, but Shelton and the Duplasses are realizing that more rigorously structured stories and beautifully constructed visuals don't need to be the enemy of cinematic naturalism.