Photo: The Last Chance: Ann (Sarah Polley) chooses to experience new love as her last few months on Earth end.

One of the most difficult film genres to manage successfully is that of the dying young person. Too often, as in Love Story, Sweet November, and the painfully self-explanatory Dying Young, the pathos curdles into bathos, and doomed youth ends up playing more like life''s grace note, with characters who are suddenly wise beyond their fears.

Death is never easy, they say, but let''s hang out a while and maybe given enough pain-free days I can unlock the secrets of the living as I taper off into the land of the dead. Characters-and films-like this are usually cloying; they may be loved and loving, but sometimes you just wish they''d get on with it already. Isobel Coixet''s powerful, compelling My Life Without Me sidesteps most of these pitfalls but demands you bring along the hankies regardless.

Tranquil and benign without being overly sentimental, it''s the cinematic version of a Cat Power tune-it has the melancholy rhythms of Chan Marshall''s most contemplative songs, where sadness and loss is a mere shadow away but regret is somehow, against all odds, held at bay. It''s beautiful. Sarah Polley is Ann, a twenty-something woman with two young girls and a loving husband (Scott Speedman), the only man she''s ever been with and her one great love. She works as a university janitor at night and spends much of the rest of the film dividing her time between her working-class family and her angry, withdrawn mother (Blondie''s Deborah Harry), who lives in the house next door to the couple''s small trailer.

After a fainting spell lands her in the hospital, the attending physician tells her she has at most two months to live, and Ann decides, not improbably, to live out her remaining time to the fullest. The catch here is that she also makes the decision not to let anyone know her time''s almost up, neither the calorie-conscious co-worker (Amanda Plummer) who wonders aloud what miraculous diet her friend must be on to lose so much weight, nor her family, and beyond. At the outset of her troubles she sits in a midnight coffee shop with pen and paper and makes a list of all the things she has to do before her death, things like "sleep with another man just to see what it feels like," and "record birthday greeting for each of the girls until they''re 18." She follows through on every one of them, too, even as her family begins to question her "anemia," and her pain intensifies.

My Life Without Me isn''t so much a film about dying as it is about having the chance to put your life in order before you do. It could have easily toppled over into the maudlin. That it doesn''t is due in tremendous part to Polley''s effortless performance as Ann; she strides through the film with a grave, secret purpose, and it heightens every "I love you" to her daughters, and every early morning cuddle with her husband. It even kick-starts a sudden, improbable relationship with Mark Ruffalo''s Lee, a lost soul recuperating from his own emotional wounds and prone to hanging out in Laundromats with a good book.

Coixet''s film begins with the quiet patter of rain on skin and holds that somehow sweetly sorrowful tone throughout, eschewing melodramatic flare-ups in favor of the laughter of children and the soft, serene sigh of the love sleeping beside you.

My Life Without Me [3 1/2 stars]
Directed By Isobel Coixet
Starring Sarah Polley, Mark Ruffalo, Amanda Plummer, Scott Speedman, Deborah Harry, Maria de Medeiros
(Rated R, 102 min.)