When Sarah Polley was four years old she entertained her Christian kindergarten class with a rendition of the Monty Python song Sit on My Face. “I love to hear you oralise / When you’re between my thighs … ” she chirruped, to the delight of her libertarian parents, who denied all responsibility when they were called to account by the school. At the age of eight, egged on by her superfan dad, she auditioned for a new fantasy adventure movie by the Pythons’ Terry Gilliam. She was already the veteran of a handful of horror films she was too young to watch, but The Adventures of Baron Munchausen was something else: an absurdist riot of special effects, the filming of which often left her sobbing in her parents’ arms after being forced to run across battlefields, with explosions all around her and nothing but a couple of cotton wool balls to protect her little ears. Gilliam has always maintained that he has kept a safe set, but the experience is one of the reasons why she is so determined not to allow her own three children to become child actors, although two are already keen, and she relented during the filming of her latest movie, because casting them as extras was the only way she could get them on set under the stringent Covid regulations. Polley is best known these days as a director and screenwriter, with credits including an autobiographical documentary, Stories We Tell, that was listed among the 100 best films of the century in a BBC critics’ poll, and the Netflix series Alias Grace, which she adapted and produced. Her latest project is Women Talking. Based on a novel by Miriam Toews about the repercussions of sexual abuse in a small Mennonite community, it boasts a stellar cast, including Frances McDormand, Ben Whishaw and Claire Foy. She is currently juggling the final sprint of post-production on Women Talking with publicising her first book. It is nine in the morning when we talk, and the blinds in her Toronto home are still drawn against the bright morning sun. Around her wrist is a bracelet of candy-coloured plastic beads made for her by her children. “Oh, yeah, it got put on me this morning. Here ….” she says, holding it up close to the screen. “It’s for colour. And it says they love me, which means I’m a great mother. So you can include that.” Her book is called Run Towards the Danger: Confrontations With a Body of Memory. It takes its name from the counterintuitive advice she was given by a doctor when she was struggling with the long-term effects of severe concussion: don’t avoid the activities that trigger the symptoms because you have to train your brain to tolerate them. Structured as a series of essays, it’s an episodic memoir of life as an actor, director and human being unlike any I have ever read: it deals with childhood bereavement, extreme stage fright, crises of pregnancy and early motherhood, and abuse within the entertainment industry, giving a bruisingly candid and intelligent account of the physical and psychic injuries Polley has suffered and surmounted during her 43 years on Earth. It’s a dialogue between two very separate time frames in her life, she writes: “The past and the present are in constant dialogue, acting upon one another in a kind of reciprocal pressure dance.” It would be wrong to describe it as an angry book, though there are many moments of great anger within it. Take her experiences on the set of Baron Munchausen, which included observing Oliver Reed viciously stamping on the foot of a 17-year-old Uma Thurman; and being forced to work ridiculous hours in perilous conditions as the film roistered past all its budgets and deadlines. The chapter is titled Mad Genius, and challenges the fetishising of irresponsible creativity. When, in adulthood, Polley learned that Gilliam was about to cast a child actor as a lead in another film, she emailed him, spelling out her trauma. He shrugged it off, flippantly questioning her memories and effectively gaslighting her. A special effects technician from Munchausen had already apologised to her, but it was only when fellow actor Eric Idle spoke out in her defence that her voice was finally heard. “She was right. She was in danger. Many times,” he said. Yet, in an extraordinary example of the “reciprocal dance” between past and present, when we discuss her children being on set for Women Talking, she recalls a moment when she herself almost lost it as a director, slipping into a vivid present tense as she speaks. “The light was fading. There’s this crane shot. My kids are supposed to be sitting on a hay bale with a bunch of other kids playing. It’s the biggest shot I’ve ever done in my life, and we have five minutes to get it, and every time we bring the crane in, my middle kid pulls all these faces right into the camera,” she says. “And there’s this moment where I thought if I hadn’t had the benefit of a childhood trauma, there’s no chance I wouldn’t be losing my mind with my kid right now. I had a moment of extreme empathy for film-makers being horrible to everyone, including children. It doesn’t make it OK or right, but it’s really complex when you have 100 people standing around and millions of dollars being spent.” A day after the interview, she emails to say it hadn’t occurred to her until now that Gilliam never lost his patience with her on set. “I think I should acknowledge that about him.” The most dangerous, and in some ways, most significant, chapter in the book is about her dealings with the Canadian chatshow host Jian Ghomeshi, who in 2014 was put on trial for allegedly assaulting a number of women. He has always maintained his innocence and was found not guilty. Polley first met him through charity work when she was a child star and he was in his 20s. She claims that at the age of 16 she had an abusive sexual encounter with him. While not part of the trial, she considered testifying against him. Her children were small, and her husband is a legal academic, so they had a wide circle of lawyer friends to consult. Most advised her not to testify because of the damage that interrogation in the witness box would do to her and her family. “I made the decision not to come forward,” she writes. “I had too much information about what would happen … ” Another reason she says she didn’t testify was because she thought her subsequent behaviour would mean her evidence wouldn’t be believed. “I am good natured, flirty, and almost happily diminish myself,” she writes, of a TV interview with Ghomeshi, during the publicity round for her 2011 film Take This Waltz. Ghomeshi was acquitted in the criminal trial and has not responded to Polley’s allegations (the Guardian reached out to him through his production company Roqe Media but received no response). “It’s really easy when you’ve had a really horrible experience to become really passionate in your language,” she says. “I believe strongly that if you’re going to say something publicly, you need to be as accurate as you possibly can, which is not always possible in these cases, because memory is a slippery, difficult thing. But I had years to think about this. She applies the same forensic scrutiny to her childhood memories. Her mother’s death when she was 11 years old – far younger than her siblings – marooned her with a father who couldn’t cope. He neglected basic parenting responsibilities such as ensuring that she wore a badly needed back brace to correct her crooked spine (she didn’t, with serious repercussions). At 14 she abandoned home, and by 15 was living with a boyfriend four years her senior. But in her documentary Stories We Tell she presented her father as a hero, who remained staunchly loving of both her and her mother, despite discovering Sarah wasn’t his biological child. She couldn’t have exposed this other side if he were still alive, she says, but life is complicated and both portraits are true. This paradox is much on her mind as her eldest child approaches the age she was when her mother died, and she audits her own stricter parenting style. By the time her mother died she was locked into a six-year contract with Disney as the star of a hit TV show, Road to Avonlea, based on the stories of Anne of Green Gables author Lucy Maud Montgomery. She was given no time off to grieve. A year later, she brought the wrath of Walt down on her head by wearing a peace-sign necklace that had belonged to her mother to an awards ceremony attended by several high-ups involved in waging the first Gulf war. Her contract was terminated, then reinstated. She was finally released early, with a black mark beside her name, only to find herself stuck in a different sort of contract hell: a theatre production of Through the Looking-Glass, and What Alice Found There, which gave her such a disabling attack of stage fright that she threw herself on the mercy of an orthopaedic surgeon, and made her escape by submitting to major back surgery. Although she continued to act in film, she has never returned to the stage, turning increasingly in her 20s towards directing. She made her feature debut at 28 with Away from Her, an astonishingly mature meditation on living with Alzheimer’s, based on short story by Alice Munro, which earned an Oscar nomination for Julie Christie. Fame never interested her, she says. Yet in one essay, spinning out of an impromptu family holiday when the youngest of her children was just nine weeks old, she’s transported back to the misery of publicity tours for the Disney TV series – “I felt like a circus horse” – and is surprised to find herself feeling a little miffed that nobody now knows who she is. “There’s nothing more humiliating than realising that some part of you, even if it’s small, wants to be recognised by a group of wholesome schoolgirls you thought you were avoiding.” The reciprocal pressure dance of past and future took a literal turn in 2015 when she was concussed by a fire extinguisher falling on her head while she was rummaging in a lost-and-found box. In her efforts to work out why the incident had affected her so very badly she recalled suffering days of dizziness as a child after being struck on the head filming a wagon scene for a TV show. Concussion is cumulative, the doctor told her. When she asked if she’d ever direct again, he sighed and said: “I think it’s a good goal to have.” She did go back: the option on Alias Grace was about to run out, and she was determined not to let it go. She is now symptom-free, and has been having the time of her life making Women Talking. It isn’t out till autumn so she keeps having to stop herself from giving too much away. But, ultimately, she says, it’s about forgiveness: “Can you forgive, and should you forgive? What does an apology look like? And when they’re there, can there be healing? “It’s something I’ve become more fixated on as I get older,” she says, “because I think it’s really important to be engaged and vocal about injustice, both personally and in a universal context. But I am also now deeply interested in what comes next. What are we trying to build? Can it be part of the process of imagining a different kind of world?”