TORONTO - A spare, unflinching examination of a married couple coping with the tragic death of their 18-year-old son, "Beautiful Boy" is graced by a pair of equally raw, affecting turns by Michael Sheen and Maria Bello.

Sharing the theme of loss and healing with another film having its Toronto premiere -- namely "Rabbit Hole," boasting similarly stripped-down performances by Nicole Kidman and Aaron Eckhart -- this first feature by Shawn Ku cuts even closer to the bone.

With its hard-hitting subject matter and extensive handheld camerawork, the film could be a tough sell for Anchor Bay Entertainment, which picked up the picture near the beginning of the festival.

When their son, Sam (Kyle Gallner), fails to contact them following a mass shooting on his university campus, Kate (Bello) and Bill (Sheen) fear the worst. But the outcome proves even more horrible than they imagined: Not only is Sam dead, but he also was the shooter.

Their grief-stricken search for answers and telltale clues, further complicated by the constant media scrutiny surrounding them, takes its toll on their already-crumbling relationship.

Despite the inevitable bouts of finger-pointing and self-blame, the faint suggestion remains that the tragedy still could end up bringing them closer together.

Directing from the nonjudgmental script he wrote with Michael Armbruster, Ku's assured, unadorned documentary style allows his leads ample breathing room to inhabit their devastated characters, and Bello and Sheen take him up on the offer by delivering a pair of exposed, painfully honest performances.

Although they're onscreen for nearly the entire movie, Ku has assembled an interesting supporting cast, including Gallner, who's briefly but memorably shown as their troubled son; Alan Tudyk and Moon Bloodgood as Bello's brother and sister-in-law; and Meat Loaf Aday as a sympathetic hotel desk clerk.