The whole doesn’t match the sum of its parts in Nobody Walks, the new movie directed by the up-and-coming Ry Russo-Young, who co-wrote the film with Lena Dunham, creator of the popular HBO series Girls. While it is led by outstanding individual performances from John Krasinski, Olivia Thirlby and Rosemarie DeWitt, the story never quite makes that next push it needs.

Martine (Thirlby) is a young, loose filmmaker from New York who temporarily moves into the house of Peter (Krasinski), the sound editor of her latest project, a bizarre black-and-white movie about scorpions and ants eating and crawling — or something, even Martine doesn’t really know. Peter has a wife, Julie (DeWitt), and a family, but this doesn’t stop him from falling for Martine.

Martine makes quick work as a helpless home-wrecker, coming on to Peter in the family’s pool house and, later, Peter’s assistant David (Rhys Wakefield) as well. Peter is not the only one battling temptation, however, as Julie, a therapist, repeatedly deals with the approaches of one of her patients, Billy (Justin Kirk), who professes to having sexual dreams about her. The film is blanketed with these types of tensions, all of which are disturbing, perhaps none more so than the relationship between Julie’s 16 year-old daughter, Kolt (India Ennega) and her Italian teacher (Emanuele Secci). The arc of the story follows how each character manages these bizarre interactions.

Russo-Young is rather new to the scene, but Dunham has quickly made a name for herself. Dunham’s work on Girls pangs with the raw aspects of reality, but still interjects enough humor to be a genuinely enjoyable experience to watch. Nobody Walks, however, while raw, seems just plain too hard to sit through. Krasinski and DeWitt are the kind of performers who are fun to watch because of the seamless ease with which they inhabit a role; it never feels like they’re acting, even though they very much are, especially Krasinski, who is a far cry from his Jim Halpert persona on The Office. Thirlby, too, is a captivating presence whose soft eyes and gentle command let her glide across the screen. It feels like we are genuinely looking in on real lives, not a staged performance.

The film has its flashes: Russo-Young’s particular use of sound is outstanding — in one of the film’s wonderful early sequences, Peter shows Martine the capabilities of directional microphones, and we get the rush of distant traffic, the rap of fingers on a wall and the squish of a moist lemon. Russo-Young clearly has talent for her craft. Her growth as a filmmaker will be a fascinating one to witness and will surely lead to some great project. Unfortunately, Nobody Walks just misses the beat, and these flashes are dimmed by the lack of a sustained effort.

At some level, the script falters as well. There are character dynamics that are addressed but not fleshed out: Peter is Julie's second husband, and Kolt is not his biological daughter, for one. At times, it feels like we are just watching a scene unfold, rather than a carefully crafted story progress. The movie doesn't need to be uplifting, as much of real life, quite frankly, is not, but it does need to better satisfy its audience's appetite for character and story development.

This may qualify as a spoiler, but really, it isn’t. The minute Martine steps out of her car and into Peter and Julie’s beautiful Los Angeles home, clean and serene and nestled in the hills, it’s like watching a bull peak its horns through the doors of a china shop; no surprises here.