There's a deeper story here that's partly conveyed in the title but mostly delivered by the entire conceit, most of which you don't learn until it's all over.

Actress and director Sarah Polley sets up the action by telling you she's going to be telling the story of her family, the focus point of which was her fun-loving, bohemian, actress mother who passed away years ago. She asks people like her aged Dad, her brothers and sisters and family friends about her mother, their recollections of her and what made her happy (and unhappy).

Gradually a picture emerges of a woman who wouldn't be tied down and who thrived on passion, but who married the wrong man to give it to her, Polley's everyday-English-bloke style father having a more steady, even outlook on life with none of the emotional ups and downs his wife thrived on.

When she gets the chance to travel across Canada to take part in a theatre production, cast members and the director tell Polley how happy she was, and a darker part of the story emerges – that her mother fell deeply in love with the director, and that he may in fact be Sarah's biological father.

Even while you're caught up in the drama of the family, something seems suspicious. There seems to be an awful lot of raw footage of her mother's life both at home with her family and away performing, even out celebrating with the cast and crew. It's all taken with a scratchy 16mm camera and the people depicted don't quite match the older version of themselves Polley is interviewing (or still pictures of them from years before).

The reason for the mismatch is revealed at the four-fifths mark, and while it's not going to spoil the rest of the film to know it, it's still a tricksy surprise, and it seems to encapsulate Polley's meta-narrative; that what we remember about people is a continual construct of our own mind – refined, changed, subverted and distorted by other people's recollections and our own experience as we grow.

It could have been a completely fictional story about a group of people she made up, but her framing device to send the message of the film is her own family. When it's over you don't really know what's true, and that's Polley's point.

I haven't seen a lot of her other work as a director, but I love the movies she's appeared in, particularly My Life Without Me. She even elevates rare genre fare like Dawn of the Dead , and I can't wait to make my way through the rest of her oeuvre. She's a very rare thing in the film industry – as smart as she is beautiful.