Stories about the loss of a child are too numerous to count—Susan Sarandon alone has been a part of four films on the subject in just the last eight years, 2002's "Moonlight Mile," 2007's "In the Valley of Elah," 2009's "The Lovely Bones," and 2010's "The Greatest"—but they continue to be made because it's one of the most daunting human conflicts a person may ever have to face. Those who have had to deal and cope with the death of a son or daughter claim that the only way to understand what it feels like is to personally go through it. For the rest of us, "Rabbit Hole" serves as a shattering, uncompromising, fairly authentic depiction. A vast departure for director John Cameron Mitchell, best known for 2001's rock musical "Hedwig and the Angry Inch," this sobering (but not depressing) drama has been effectively adapted by David Lindsay-Abaire (2009's "Inkheart") from his own Tony Award-winning Broadway play. While the hint of stage play roots waft through now and again, Mitchell has done a fine job overall of expanding the show and opening it up enough so that things never become claustrophobic or stodgy.

From the outside, Becca (Nicole Kidman) and Howie Corbett (Aaron Eckhart) might seem like a normal married couple, in the upper echelon of the middle class and with a lovely house overlooking the Hudson. Howie heads to work each day, while Becca cooks and gardens, a former New York City executive gone domestic. Underneath this facade, however, they're barely hanging on, dealing with grief in very different ways over the recent death of their four-year-old son. Howie is up at all hours of the night watching old videos of his late child on his phone. When he drags the more cynical Becca to a support group for parents who have lost a child, she can't help but betray another set of parents who reconcile their personal tragedy by saying God must have needed another angel. "If he wanted another angel, why didn't he just make one?" Becca angrily asks. "He's God, after all." Not able to see eye to eye with how they should deal and their marriage suffering as a result, they eventually branch off as they seek to heal. While Howie grows closer to a recently separated fellow parent at the group, Gaby (Sandra Oh), Becca starts secretly meeting Jason (Miles Teller), the teenage boy who hit and killed their son.

A quietly simmering, consistently involving drama forever on the verge of exploding, "Rabbit Hole" relies on the sympathetic nature of its characters and the raw truthfulness of its story to carry it through the land of overfamiliarity. A woman of about forty who gave up her career to be a stay-at-home mom and now seems to be stuck in limbo as her former colleagues have passed her by, Becca sees it as a defeat no matter which path she now chooses. There is a quietly devastating scene where Howie heads to the office for the day and she dresses up in her most fashionable working-woman outfit to go visit her old coworkers, only to discover that most of them have moved on to bigger and better things while she has lost everything. Adding a further twist of the knife to Becca's situation is the news that her loose cannon of a younger sister, Izzy (Tammy Blanchard), is pregnant with her musician boyfriend's baby. In her eyes, based on what she herself has had to endure, Izzy doesn't deserve a child. She dare not tell Izzy this in so many words, even if it is still read on her face, and her subsequent attempts to be supportive prove misguided when she tries to give her sister her deceased son's baby clothes. Meanwhile, mother Nat (Dianne Wiest) never fails to remind Becca that she, too, lost a son and has been through the heartbreak of it. "A 30-year-old drug addict who overdosed isn't the same thing as a 4-year-old who got hit by a car!" Becca finally says in a rash moment of frustration. Nat's valid, hurt response: he was still her son, no matter how old or the circumstances involved.

In one of her strongest, most accomplished performances in several years, Nicole Kidman (2009's "Nine") is a powerhouse as Becca, stripped of vanity and unafraid to not always be seen in the kindest of light. Kidman's lack of inhibitions here no doubt come from her trust in the material. Becca is a juicy, complex character to portray, a woman who puts up a front as she attempts to move on with her life, yet can't seem to find her way out of the darkness eating away at her from the inside. That she is someone who isn't particularly religious and doesn't rely on faith is a fascinating added stroke to her role, and also pivotal. Director John Cameron Mitchell does not look down on Becca for her aversion to religion; if anything, the film seems to side with her in her views while exploring how someone who doesn't have a relationship with God must look for guidance and learn how to heal by other means. Becca's initially awkward but compassionate bond with Jason, affected in his own way at the knowledge that he caused the death of another person, no matter how unintentional it was, is dealt with in a restrained, certainly moving manner. A comic book about parallel universes that he is creating called "Rabbit Hole"—hence the title—seems to be an unimportant detail until Becca reads it and its significance is revealed. Proof that personal solace can come from the unlikeliest of places, Becca is comforted by the idea that there could be countless versions of herself out there living alternate lives, some of them happier than her own. She likes the thought of that.

In a motion picture that very much belongs to Kidman, her co-stars are no laggards. Aaron Eckhart (2009's "Love Happens") indelibly plays husband Howie, who, unlike Becca, acknowledges that they are in a bad place even as he is reluctant to fully accept what has happened. Unsupported by his wife and distraught over her unspoken actions of seemingly erasing their son from their house—she takes down all his artwork from the refrigerator, gives his clothes to Goodwill, etc.—Howie finds a much-needed person to confide in when he starts hanging out with Gaby. In a lesser, more predictable film, these two would have an affair, but the idea is only ever suggested and the way their friendship resolves itself is appreciably low-key and honest.

Sandra Oh (2010's "Ramona and Beezus") is wonderfully inspired casting as Gaby, the underrated actress embracing the rare chance to play someone who isn't a doctor, teacher, or other authority figure. As Jason, newcomer Miles Teller is a great find, expressing so much with a face that is young but forlorn. His scenes with Kidman are some of the best, the two of them working off each other with hesitant affection as the troublesome history that links them hangs over their heads. Finally, Dianne Wiest (2008's "Passengers") lends dignity and heartbreaking pathos to Becca's mom Nat, whose own tribulations in life have been ignored for too long. A stunningly acted and written heart-to-heart where Nat frankly explains to Becca how the pain of losing a child never goes away, but changes and evolves over time, is given all the more depth and breadth through Wiest's aching reading; here's an actress who doesn't just act her roles, but convinces to the point that she makes the viewer believe she's living them.

The conflicts that the characters in "Rabbit Hole" are facing are not easily fixed. Some aren't even capable of being corrected. The goal, then, is for them to get to a place where they at least know they'll be all right. After all, the death of a child is not something you "get over," but something you just have to learn to endure. Despite their problems, Becca and Howie never stop loving each other. Though director John Cameron Mitchell might have done well to add a few on-screen beats where the warmth and strength of their marriage is cemented, this is a minor issue. The choice to not wrap things up in a neat bow only proves that the makers understand the obligation to be truthful with the story they're telling. They don't dare betray it.