See itAt first it feels like a vanity project: an elaborate exercise in navel-gazing from a famous actor convinced there must be something awfully important about her own middle class upbringing.

It is to the credit of Canadian actor/writer Sarah Polley that her debut documentary, Stories We Tell, evolves from a talking heads sit-down exploring family relations and the freewheeling personality of her late mother, Dianne (she died young, when Polley was 11), to something much more ambitious.

The film begins with a voiceover of a Margaret Atwood quote: “when you’re in the middle of a story, it isn’t a story at all, it’s a confusion.”

The enunciator is a velvet-voiced elderly Englishman talking into a recording studio microphone. We learn he is Sarah’s father, retired British actor Michael Polley. We also learn where the confusion comes in: Dianne slept around, and knowledge of this led Sarah to question whether the man who raised her is her biological father. Stories We Tell is largely about Polley’s search for answers.

“Yay” or “nay” is one of Stories We Tell’s least interesting points of inquiry. Polley’s interviews with people who knew her mother – and in turn know her, which helps generate candid and sometimes amusing responses – are nice enough but hardly heart-warming or intellectually rousing material.

Well into its second half, the parameters realign in subtle but profound ways. The cleverness of the film’s title, which suggests narrative has greater currency than truth, comes into play.

Polley attempts a great deal: to examine the arguably inherent fraudulence of the documentary medium, the unreliability of memories and cinema’s capacity for obfuscation and sleight of hand. Against the odds, her elaborate family album, folded in mystery, leaves a lasting impression.

Stories We Tell’s Australian theatrical release date: September 26, 2013.