This is a clear development of themes that Canada's third-weirdest auteur (after David Cronenberg and Guy Maddin) has been working in The Adjustor and Exotica.
The plot unfolds in several interleaved time periods, and a few dizzying revelations and connections might make you want to go back and see it again to confirm what you've been led to suspect. Lawyer Mitchell Stephens (Holm) arrives in a small town in British Columbia. His aim is to get the parents of children killed in a schoolbus accident to retain him in suits against those responsible.
It is at once apparent that Stephens, suffering through his own parental trauma, is as much concerned with sorting out his own demons as stirring up those of the town. We flash back to the days before the accident, the gradual recovery afterwards and Stephens' flight north, learning more and more about the people involved in the knot of tragedy. The focus slowly shifts from the lawyer to Nicole (Polley), a wheelchair-bound teenage survivor of the disaster, as she comes to a decision about how best she can cope with her grief and guilt.
An evocative parallel with The Pied Piper underlines a more complex set of emotions than the cinema is usually keen on depicting. It's a tactfully acted film, beautifully shot in snowy widescreen, subtly scripted and directed with a rare touch. The subject is as painful as it is possible to imagine, but the treatment, while never preachy or affected, is humane, insightful and extremely moving.