The human face is one of the most powerful tools in a filmmaker’s creative arsenal. Dreyer knew it when his camera lingered on Maria Falconetti’s anguished eyes in The Passion of Joan of Arc (1928). Spielberg knew it when the reverse dolly zoom showed the terror Roy Scheider experiences when he thinks his son is in danger in Jaws (1975). And Sarah Polley knows it in Stories We Tell, a documentary that relies almost entirely on talking heads, with some home movie Super 8 footage thrown in to the mix. There’s very little in the way of visual flair to the film, meaning that Polley relies on the power of her interviewees’ faces to ensure that their narrative has impact – while her father’s words are powerful, it is his glance away from the camera as he tries to stop himself crying that stays with you.

The eponymous stories are recollections of the director’s mother, who died when Polley was 11, from her family and friends. There’s Johnny, Sarah’s oldest brother, who has a playful sense of humour, and Geoff, her mother’s ex-colleague who seems reluctant to share his thoughts. From the very beginning, however, the star of the show is her father Michael, who has written a memoir that he narrates throughout, and this forms the core of the film. Michael is eloquent, thoughtful, funny and often painfully candid. As Sarah digs deeper into her mother’s history, Stories We Tell becomes more than just personal remembrances, but a study of memory and an examination of family dynamics that reveals a tenderness beneath the apparent dysfunctionality.

If it all sounds too heavy or complex, then Polley’s assured direction and the interviewees’ oratory skills ensure that it is far more enjoyable than may appear. Human faces tell much of the tale, whether they are gasping in disbelief, laughing at a happy memory or staring sadly beyond the camera, each person she speaks to brings both warmth and humanity to their version of events. Polley herself isn’t in front of the camera very often, but her skill in the editing room keeps the film on course, and the unfolding nature of the narrative owes as much to the way she takes on the role as master storyteller as it does to each individual. The main criticism of the film is that it is unsure how it should end, and the pace suffers as a result of this. However, the multiple conclusions work to wrong-foot the audience regularly as well as to draw out new revelations and themes from the narrative. It is always a joy to watch.

Stories We Tell could have been terrible – focusing on the director’s family could have led to the kind of introspection that comes across as too self-involved. However, by using her very intimate personal story to examine universal themes such as memory and family, Polley has created an accessible, thought-provoking and frequently moving documentary.

Stories We Tell is playing at Edinburgh Film Festival on 21 & 22 June