Eve Ensler begins her memoir with a simple dedication: “For every woman still waiting for an apology.” Ensler counts among these women herself. The award-winning American playwright and activist who has spent decades campaigning globally against anti-female violence, was ritually assaulted by her father, Arthur Ensler. It began as sexual abuse when she was five. By the time she was 10, he was choking her, punching her in the face, threatening to stab her and beating her with belts and paddles in sickening acts of pain and humiliation. Eve’s mother looked on in silence. Her family was pitted against her. Arthur died 31 years ago; he had not uttered any words of repentance.

Earlier this month, the TV presenter and comedian, Ellen DeGeneres, spoke of her sexual abuse at the hands of her late stepfather. Her mother apologised for not originally believing her daughter’s story. It was a cathartic #metoo moment. Eve Ensler can be afforded no such moment.

So how can the scarred survivor find psychic liberation from her abuser after he has died, when accountability is evaded and a reckoning forever out of reach? Ensler, at the age of 65, grapples with this difficult question in the course of this profound, imaginative and devastating book.

Ensler has, before now, touched on the legacy of her abuse. In her 2013 memoir, In the Body of the World, she described feeling exiled from her body and “trying to find a way back”. This is what had led her to document other women’s relationships to their bodies in The Vagina Monologues (1996), her seminal stage play that sparked a worldwide movement to end gendered violence in the creation of V-Day. Some of the women and girls she spoke to – over 200 in total – had also become exiled from their bodies and were “desperate for a way home”, she wrote.

This latest memoir returns her to the violated body of her own five-year-old self, and the bloodied and beaten teenager, but through a central paradox at the heart of the narrative: The Apology is written as a letter of penitence from Arthur to her – and she, the writer and daughter, undergoes a creative out-of-body experience to inhabit his voice, body and mind.

Dramatically, it is horrifying and mesmerising in equal measure, both in its depth of inquiry and its detail. The letter writing device channels Arthur’s intimate, confessional and not always detestable voice, speaking from the tortuous vacuum of his limbo in afterlife.

The chronology traces the roots of his dangerous narcissism to an unhappy childhood and describes, with astonishing pathos, the boy whose lonely life was built on false charm and self-delusion. He had an over-adoring mother, an exacting father, and a bullying brother whose sadism is mirrored in Arthur’s adult attacks on his daughter.

The tone shifts when Eve is born and here she conjures his sleazy joy at her birth with such ominous foreshadowing that we fear for tiny Eve, even in her cot: “You were my life force returned. You were the gift of passion made out of my own sperm and flesh … I would lean close and inhale the sweet scent of your baby breath. I would cover you in your little white blanket, and as I wrapped it around your tiny frame I would feel this sensation of falling, falling tumbling into a milky universe that offered a safety and a delight I had never known.”

Arthur is both human and monstrous – a dashing ice-cream company salesman from a New York City suburb and a paedophile, an embodiment of toxic masculinity and a fallen Lear (“I cursed you Eve, and cast you from my land”). He is first propped up by mealy-mouthed mitigations of his actions and then, slowly, undone by his guilty betrayal of his most loved daughter: “What is this burning sensation in my chest? Oh Eve, oh Eve, is this your heart inside me? ... Oh anxiety, Oh loneliness, oh despair. Despair.” But in spite of, or perhaps because of, his hyperbolic, theatrical language, his apology, when it comes, retains a hint of self-pity and histrionics.

The Apology is a complicated act of ventriloquism and Eve’s anger sometimes glints within his words. At one point, she sounds like a modern-day Circe, vanquishing the spectre of this abusive father by turning him into a small, scuttling creature, her contempt for him forced out of his mouth as self-loathing: “I grow sick of these horrific confessions and myself. Rattling and oinking on and on. Struck like an unctuous pig spinning on a torturous spit of gangrenous self-centredness.”

The young Eve emerges as a girl of immense inner steel in the face of systematic beating and bullying

A double-narrative emerges in the course of the book and it is as much her story as his; we see her change from a naturally effervescent child to a young woman battling with drink, drugs and suicidal self-destructiveness. His abusive psychopathology is correlated to its damaging effects on her psyche (“You were always apologising, begging for forgiveness. I had reduced you to a daily degrading mantra of ‘I’m sorry.’”).

The young Eve emerges as a girl of immense inner steel, a “fierce and unstoppable daughter” in the face of systematic beating and bullying. There are quietly heroic moments of resistance that are both triumphant and tragic for her strength in acute adversity. In one instance, Arthur Ensler creeps into her bedroom to abuse her and is taken aback by her stiff unresponsiveness. She has wilfully vacated her body – the bodily exile that she speaks of years later. It is the only form of protest left to her and it works to repel him.

In another instance, he stops beating her bare, bloody bottom when she forces a fake smile, despite the pain, and thanks him for it. He never punishes her in the same way again. Both these moments show Eve’s courageous negotiations of power, even when he presumes to render her powerless.

This book, in the end, is an act of imaginative empathy that seeks to understand the monster father and turn him into the human one, and also its own form of literary retribution that calls out his crimes.

Can creative exhumation of this kind really free an abused adult from a lifetime of childhood suffering? Ensler’s book does not – cannot – provide a definitive answer but there is a moving power and poetry to the prose that rouses Arthur from his grave and holds him to account. The book ends with the words “Old man, be gone”, and one feels – hopes – he has left his limbo and is in permanent banishment, his daughter at last free.

• The Apology is published by Bloomsbury (£16.99). To order a copy go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £15, online orders only. Phone orders min p&p of £1.99.