Sarah Polley, Stories We Tell, 2012, color and black-and-white, sound, 108 minutes.

THOUGH STORIES WE TELL is Sarah Polley’s first documentary, it continues a theme explored in depth in her two features, Away from Her (2006) and Take This Waltz (2011): the pitfalls of married life and third-party complications. The conjugal couple in question in Stories We Tell is Polley’s own parents, the outsider a man who lived three hundred miles to the north of them. To unravel the mystery of her very origin—which is rooted in the mystique surrounding her charismatic mother, Diane, who died when she was eleven—Polley interviews family members and Mom’s former friends and colleagues. Gracefully commandeering and assembling her project’s many layers, Polley goes on a psycho-archaeological dig that avoids solipsism through meticulous reporting and structural cleverness.

Polley, who began her career as an actor (she’s best known for 1997’s The Sweet Hereafter), appears intermittently throughout Stories We Tell, often at a soundboard, gently instructing her father, Michael, who is recording a narrative of his life with Diane in the third person. At other times, she is seen but not heard, interrogating her four older siblings from offscreen. “Who fuckin’ cares about our family?” one sister snarls during the film’s opening minutes. It’s a valid query, one that Polley may have included preemptively, anticipating the resistance of the skeptical moviegoer wearied by the seemingly interminable supply of shoddy, personal documentaries.

Yet what Polley unearths about her parents quickly makes viewers invested in them. Both actors, Michael, a British transplant, and Diane met in Toronto’s theater scene in the 1960s; he abandoned performing to work for an insurance company after they started having children. In his sit-down interviews with his daughter, Michael, chain-smoking and wearing hearing aids in both ears, reminisces with alarming candor about his shortcomings in the marriage: “A night with a dead wombat might be more exciting than a night with me after twelve years.” He later admits that he encouraged his vivacious wife, who floats throughout the film as a beautiful, dead ghost, to take a lover—which is just what she did while acting in a play in Montreal in the late ’70s.

Viewers may wonder whether the relationship trajectory of Polley’s parents inspired that of the married couple who have regressed fully into sexlessness in Take This Waltz, which she also wrote—a fact/fiction divide that drives much of Stories We Tell. Calling attention to the ever-porous boundary that separates true from false, Polley presents the recapitulation of her mother’s affair (and its effects on Polley’s family) as a chronicle that varies widely depending on who’s speaking. Highlighting the vagaries of memory—and how these discrepancies shape or corrupt the official record—is nothing new in documentaries. Yet Polley destabilizes verities even further by including Super 8 footage of her parents and her mom with her paramour that I was convinced was authentic, decades-old documentation but that is later revealed, quite unostentatiously, to be staged reenactments. It was at this moment that the title of another first-person project—Yvonne Rainer’s—came to mind: Feelings are facts, a deceptively simple declarative sentence that Polley cannily parses.

Melissa Anderson

Stories We Tell opens in New York on May 10 and nationally on May 17.