The Greatest treads familiar thematic ground, but does so with urgency and genuine emotion. Countless movies have depicted the complex burdens of the grieving process, the difficult balance between remembering a loved one and adjusting to the harsh truths of a revamped reality without him. Few have done so with as eloquent a combination of visual texture and dramatic richness as writer-director Shana Feste’s striking debut, a success at the 2009 Sundance Film Festival finally getting its much deserved theatrical release.

The film begins with a prelude that offers a poignant snapshot of the whirlwind courtship of teens Rose (Carey Mulligan) and Bennett (Aaron Johnson), which is cut short by the latter’s shocking death. But the picture first reveals the unabashed sincerity with which it treats its subject in a virtuoso unbroken take employed shortly thereafter.

As Bennett’s mother Grace (Susan Sarandon), father Allen (Pierce Brosnan) and his brother Ryan (Johnny Simmons) ride home from the funeral, the camera remains planted on the family in a three shot from a middle distance. Allen looks straight ahead, maintaining his composure as his panicked eyes reflect the profound weight of the reality of his son’s death settling in. His wife and son, alongside him in the backseat, stare hopelessly, silently out the window. Not a word is said, but much is revealed.

That approach defines Feste’s lush, widescreen portrait of deep rooted pain. Within a world of privilege — full of manicured homes and seaside towns — the writer-director zeroes in on the specter of a family breaking down and experiencing a rebirth. She balances a Sirkian grasp of open, earnest melodrama with a palpable sense of the different ways individuals cope with such an enormous trauma. While Allen bottles things up and gamely carries on, Grace awakens sobbing daily and never stops, while Ryan turns to therapy sessions and drugs.

Things grow more complicated when shortly after the funeral Rose arrives and announces she’s pregnant by Bennett, with nowhere to go. The sharp, strong teen becomes a tonic for Allen and a nuisance for Grace; he sees an unexpected blessing amid terrible darkness, she sees a usurper of sorts, a young woman threatening to obfuscate her efforts to preserve Bennett’s presence in their daily lives.

Mulligan has been more heavily hyped for her Oscar nominated performance in An Education, which also played successfully at last year’s Sundance, but the part of Rose presents a comparably steep challenge. She is the critical character in the picture, the precipitator of change and acceptance in the family’s life. To buy that Rose could be welcomed into their home despite being a stranger (Bennett never introduced her to them) the audience must share the family’s belief that she and Bennett truly loved one another, even though their physical romance was but a brief summer whirlwind.

In the part, Mulligan radiates strength and sincerity. There’s always the sense that she means what she says, with charm, moxie and the depth of an old soul. The actress facilitates Feste’s portrait of a romance that was more than the flash in the pan it seems. Between her scenes with Johnson, relegated to inserts and flashbacks but always imbued with the metaphysical nature of true love, the steadfast way she consumes stories about him and the urgent sadness with which she tells Allen of the depth of their connection, the actress makes us believe Rose has earned the right to help the family heal.

The Upside: Carey Mulligan gives another terrific performance, and Shana Feste ably blends her melodramatic leanings with a quieter, subtler portrait of grief and healing.

The Downside: Occasionally, as in a subplot in which mom Grace cares for the comatose man (Michael Shannon) who was the last person to see her son Bennett alive, the movie gets a bit too heavyhanded.

On the Side: The movie premiered at the 2009 Sundance Film Festival to critical acclaim, but was overshadowed by the phenomenon of Carey Mulligan in An Education.