Some of the best and most important films ever released have explored a simple, powerful idea: All "truth" is suspect.

In 1950, Akira Kurosawa released Rashomon, which used multiple perspectives to repeatedly retell the story of a single crime, with each retelling revealing the storytellers' egotistical biases. Later films, including David Fincher's Fight Club and Christopher Nolan's Memento, have tackled the subject with similar success.

Now, actress/director Sarah Polley (Away From Her, Take This Waltz) is out with a powerful documentary, Stories We Tell, which applies the same lens to Polley's own family. The Genie Award-winning film is not only a highly personal cinematic achievement, but a fascinating exploration that morphs truth from a black-and-white absolute to a subjective, fluid process — never static, but always evolving through subjective memory and experience. It is not just a must-see documentary, but one of the must-see films of 2013.

Stories We Tell was shrouded in secrecy when it premiered at the Toronto International Film Festival in 2012. There was no plot description — only a vague explanation that this film was "a personal essay on the intractable subjects of truth and memory" about "a single family as they look back on decades-old events." No names were given and no details uttered until the film hit screens and news hit the Canadian wire. It wasn't until the premiere that anyone knew that Stories We Tell wasn't a film about a family Polley had discovered, but about her own. The Polley family's story is rife with the sort of meat usually found in Hollywood productions — drama and secrets, scandalous news bites, celebrity anecdotes, and an insane coincidence: That Polley's parents, Diane and Michael, performed in a play that foreshadowed the events their family would later experience. (This review will avoid specifics; the film is best experienced without its details spoiled.)

Unlike most personal documentaries, which thrive on one ultimate point of view, Stories We Tell builds a narrative out of competing and divergent memories. Polley reveals the story as a collective, with each family member eagerly offering their unique version of events, without any priority placed on one person's recollection over another's. In a late moment in the film, Michael Polley wonders if his daughter's intent is not strictly an artistic angle, but rather a way to avoid the real truth. She concedes that he may be right.

As an investigation of truth, Polley starts at the beginning — not the beginning of the story, but of her search. Audience members are introduced to each "storyteller" just as they settle into their seats. Astonishingly, Polley even manages to give her late mother (actress/casting director Diane Polley) the same introduction, relying on old black and white footage of Diane before a performance, sitting anxiously, waiting just like every other participant in the documentary. Showing these pre-shoot jitters lets each person begin with equal footing, and bridges the gap between the film and its real-life participants. They aren't just experts in their own experience, talking heads who only exist (to the audience) as cinematic characters, but real people who react to and learn from this new collection of insights. Storytelling creates "unintended fictions," says Polley, and "truth begets other truths," says Polley's sister.

But the audience isn't merely a collection of innocent bystanders or curious onlookers. Through revealing moments behind the scenes, shots in between takes, shots of Polley silently reacting, and the discrepancies that crop up from story to story, the audience becomes tertiary investigators of the "truth." Through memories, Polley reveals many all-too-human foibles — how easily we can make bad choices and assume the wrong thing, how we can lie, and how we can tell the "truth" without revealing any truth at all.

Stories We Tell has been widely praised since its festival premiere, but one complaint has dogged even the most effusively positive reviews: That Sarah Polley's perspective isn't balanced with that of her storytellers. In the early moments of Stories We Tell, Polley refuses to offer opinions and responses — the camera even cuts away when she's asked for her memories. But that changes over the course of the film; scenes of Polley silently reacting to testimonials make way for more active involvement. When she becomes the active participant in the growing narrative, the audience listens to her read emails and watches her recreate recent experiences.

There is no magnetic sense of *I*, however, because this isn't her telling her story. It is an exercise in immersion — in listening, revealing, and most importantly, reacting. The film isn't a manifesto, or egotistical explorations like the players in Rashomon; it's Polley's reaction to a jarring, interpersonal whirlwind. It can't be definitive because it isn't Polley recollection; it's Polley living within this story as she struggles to find her own truth. The film's true message is summed up in its opening lines, which come from Margaret Atwood's Alias Grace:

When you're in the middle of a story, it isn't a story at all, but only a confusion — a dark roaring, a blindness, a wreckage of shattered glass and splintered wood, like a house in a whirlwind, or else a boat crushed by the icebergs, or swept over the rapids, and all aboard are powerless to stop it. It's only afterwards that it becomes anything like a story at all — when you're telling it to yourself, or to someone else.

In the film, Sarah Polley is the blind wreckage in the middle, navigating ephemeral thought as it becomes an all-too-real reality. By choosing what to reveal, and the connections that are made between recollections, Polley is forming her story, absorbing details, and looking for the truth in a myriad of competing memories.

And that's what makes the documentary intensely truthful and compelling — the complete lack of stating any full truth, of the egotism that comes with a perfectly crafted certainty. The stories repel and attract each other, with each player's truth creating another truth in each viewer's experience. And even then, Stories We Tell won't let you feel entirely secure in the opinions you've formed — which is, in the end, the real truth anyway.

Girls on Film is a weekly column focusing on women and cinema. It can be found at every Friday morning. And be sure to follow the Girls on Film Twitter feed for additional femme-con.