Kristin Scott Thomas' performance in I've Loved You So Long is one of a small handful of highlights by which people will remember this year in movies. This is acting at its most exalted.

For all its moodiness, despair and disconnect, I've Loved You So Long is all about acknowledging human error and embracing ties -- to family and life -- that can't be undone.

Their characters' desire (Scott Thomas and Zylberstein) -- no, need -- to repair their fragile bond feels as achingly real as the mother lode of hidden pain that gets exposed by the work of these two great actresses.

Philippe Claudel gives his heroine unusual depth, which Kristin Scott Thomas reveals with unusual passion.

Performances this strong and direction this sensitive make us simply grateful to have an emotional story we can sink our teeth into and enjoy.

But let's be honest: Any actress can do melancholy; it takes a special talent to recognize that there's a certain luxuriousness, a certain joy, to be found in longtime self-hatred.

This film teaches the rewards of patience for directors, for actors and for audiences, too. The compelling reality of Juliette's plight comes from how subtly and gradually she emerges from her carapace.

This is a picture of quiet observation, contained emotion, the hush before the cathartic scream.

This is one of Kristin Scott Thomas' most inspired performances.

The film deftly sketches a sibling relationship complicated by obligation, guilt, mistrust, and, not least, an abiding love.

It's no insult to the rest to say that this is one of those films that sells itself on the strength of a single performance.

Claudel turns out to be very good at the psychology of intimacy. An observant man, he has assembled a large (and, to us, unknown) cast of actors around his star, and he dramatizes her slow reawakening with an infinite number of small, sharply etched details.

A revelation comes near the end that is both tremendously moving and a bit disappointing, in the way that the solutions to great mysteries frequently are. This turn does not diminish the accomplishment of Ms. Scott Thomas's deep, subtle and altogether stunning performance, but it does alter the scale of the movie, turning it into a more manageable, less existentially unsettling drama.

Philippe Claudel's direction is both probing and delicate, and Scott Thomas's face, even immobile, keeps you watching, searching for hints of her character's past, unable to blink for fear of missing something vital.