Based on the richly textured novel by Stewart O'Nan, "Snow Angels" is a searing portrait of three interconnected families living in a small Pennsylvania town, their lives affected and, in some cases, irretrievably altered through a series of tragic events. As faithfully adapted for the screen and directed by David Gordon Green (2004's "Undertow"), the film's escalating power and cumulative emotional impact can be attributed to the care that this indie-minded filmmaker brings to the project. Both in his depiction of a wintry landscape of lost souls and in his painfully accurate portrayal of characters struggling to make their way in a world that oftentimes seems cruelly unfair and confusing, "Snow Angels" rings resoundingly true.

Representative of four relationships in varying states of growth or disrepair, the picture's center of gravity is teenager Arthur Parkinson (Michael Angarano), who watches as his parents, Louise (Jeanetta Arnette) and Don (Griffin Dunne), mutually separate and his college professor father moves out of the house. At school, the cutely bespectacled Lila (Olivia Thirlby) has her eyes on him, but her obvious attempts at starting something romantic are lost upon Arthur, who can't imagine someone would be interested in him. At his job as a busboy at a local Chinese restaurant, he works alongside his former babysitter Annie (Kate Beckinsale), at the time a teen herself and now a somewhat hardened and overworked mother going through a difficult divorce with perpetual screw-up of a husband Glenn (Sam Rockwell). Against her better judgment, Annie has begun a seedy affair with Nate Petite (Nicky Katt) behind the back of his wife and her best friend and coworker Barb (Amy Sedaris). When the unthinkable strikes after Annie's and Glenn's 4-year-old daughter Tara (Gracie Hudson) goes missing, it is the catalyst for everyone to finally face what they mean to each other and where they stand in the choices they've made.

"Snow Angels" begins with what could only be looked at as a harbinger of doom to come—Arthur's marching band practice on the high school football field is suddenly disrupted when two nearby gunshots ring out in the frosty air. Rewinding the clock by several weeks, the film aims to explore what leads to this fateful moment in time, and for 106 minutes, writer-director David Gordon Green holds viewers in rapt attention even as they occasionally find themselves shrinking down in their seats, aware (even if subconsciously) of the inevitable conclusion being built toward. Audiences in search of a frothy good time at the movies might as well look elsewhere. While there are lighthearted moments to be had, and the adorably burgeoning relationship between Arthur and Lila offers glimmers of revelatory hope, "Snow Angels" is bleak and uncompromising in its tone and narrative turns. At the same time, save for a somewhat forced opening monologue by the overbearing band leader (Tom Noonan), the film is never less than glaringly authentic.

The ensemble of characters are true originals, feeling, looking and sounding like real people rather than vaguely developed screenplay pawns. In the very specific milieu director Green is working within, his characters are flawed, sometimes troubled, but sympathetic even in spite of some of the less savory choices they make. All of them are simply trying to navigate the circumstances they've found themselves in and, unfortunately, a map has not been made to guide them.

In a film of emotionally rattling moments, it is in the smaller, quieter interludes of human connection and reflection that are often most poignant. The way, for example, that Arthur gives Lila a pencil from his locker as a spur-of-the-moment present, is naive in the extreme, and yet exactly why Lila is charmed by him. A conversation they later have in Arthur's bedroom where he tells her about his remembrances of having Annie as a babysitter are heartbreaking in their subtle comments on the way innocuous childhood memories have a way of holding greater nostalgic value years later. Another moment in which Arthur and his mom reminisce over a photo album is unpredictably insightful: "You can always tell in pictures whether someone's smile is authentic or not," Louise says, to which Arthur comments on how people don't bring cameras to sad occasions in their lives.

The actors in "Snow Angels" are all working at the top of their games, seemingly delighted to be able to sink their teeth into unusually complex, three-dimensional roles. As Arthur, Michael Angarano (2007's "The Final Season") is just about as good as it gets for male actors of his late-teen/early-twenties age group. Angarano has an everyman quality about him that makes him instantly identifiable, but also the kind of face that you just want to hug. He is perfect as Arthur, an otherwise ordinary teenager whose sensitivity and heart run a little deeper than most. Because of this notion, he and Lila, an embracer of the offbeat who refuses to conform to stereotypes, make for an undeniably sweet couple. Olivia Thirlby (2007's "Juno") is an utter delight as Lila, worldly and intelligent yet mischievous and vulnerable.

As the morally torn Annie, Kate Beckinsale (2007's "Vacancy") is something of a revelation. Beckinsale has been superb in the past, but, like Jennifer Aniston in 2002's "The Good Girl," she's never been given the chance to essay a role with quite so many layers and interior demands. Overcome with guilt over what has happened to daughter Tara, Beckinsale starkly digs into the darker corners of a person's psyche. Her final onscreen look and utterance of "Oh my..." is especially haunting. In perhaps the most difficult part to pull off, Sam Rockwell (2007's "Joshua") is mesmerizing as Glenn, a man who can't seem to ever do right—his forgetting to bring a stuffed bunny he has bought for Tara on one of the their days spent together is particularly symbolic of this—and whose mounting religious faith is at direct odds with the actions he takes in the third act. In lesser hands, Glenn could have become over-the-top and too broadly played, but Rockwell makes him as credible as the rest of the characters.

Finally, in a bit of against-type casting that pays off in spades, Amy Sedaris (2006's "Strangers with Candy") reels back her usually comedically-inclined onscreen personas as the down-to-earth Barb, a woman trying to come to terms with both an unraveling marriage and the betrayal she experiences from best friend Annie. That Barb still sticks by Annie when the chips are down is clearly representative of Barb's forgive-and-forget nature. This is Sedaris' juiciest film role to date, and one that proves she is just as adept at drama as she is at comedy.

In a still-early year, "Snow Angels" rises above almost everything else that has thus far been released. Emanating a sense that what happens to these characters not only could happen in real life, but has, the film is mesmerizing in its sharp, fully-realized gaze at lives approaching a crossroads from which only some of them will reach the other side. Beautifully photographed by Tim Orr (2007's "Year of the Dog"), taking advantage of his chilly, ice-drenched setting, "Snow Angels" is so provocative and effective because of how director David Gordon Green handles the tough material, lending equal weight to both the extraordinary and deceptively mundane moments of life in motion that make all of us startlingly, stingingly and intensely human.