There’s nothing as satisfying as settling into a new Linda Greenlaw memoir and feeling like one is “on island” or at sea with her. But Lifesaving Lessons is very different and a bit shocking.

Greenlaw tells how she becomes an accidental mother to a 15-year-old girl who had moved to Isle au Haut with an “uncle” who supposedly helped her get away from a bad home back in Memphis.

Uncle he’s not, but sexual abuser and predator he is.

The tale is a page-turner, as Greenlaw is nominated by island women friends to take on the care of this young woman, identified with the pseudonym Mariah.

Greenlaw and her charge — who had briefly been her sulky stern man one summer — don’t have an easy time settling into their “shotgun” relationship. But that’s this book’s gift: seeing the trust needed for the bumps in the road (and, oh, are there bumps) as Greenlaw decides to become Mariah’s legal guardian.

But, as Greenlaw admits, mothering doesn’t come naturally for her or with an operating manual for a strong-willed, shaken and compass-less teenager, making the work of swordfishing look more manageable than this sudden parenting.

Together, they learn to laugh after the early crises pass, and Greenlaw tells Mariah, “When people ask where the hell you came from, I tell them the stork left you on my doorstep when you were 15.”

Once the horrors come out, through Mariah’s reluctant disclosures to friends and professionals, she learns to trust, and tectonic plates begin move in this tight-knit community that didn’t expect to see such a dark side of their year-round life together.

Greenlaw is an ace at narrating conversations and conveying the challenges of guiding her “accidentally acquired” daughter through the crisis of sexual abuse, legal action, seeking steady ground and getting on the road to becoming a healed, responsible young woman.

It’s key that Greenlaw’s own family—her parents and two sisters—offers steady and essential support to Mariah and Greenlaw herself through this rocky time, she emphasizes.

And as for what Greenlaw is able to give teenage Mariah at a critical time, she lists “her basic needs, a supportive community, an exclusive education, a wonderful father figure” in her close friend, a doctor, “and a devoted and close network of friends and family”¦”

The island experiences several awful events even after Mariah’s “uncle” and abuser/predator is found out. On man is arrested for sex with a minor. An island worker overly friendly with young women commits suicide. And islanders learn that a sex offender was living among them in what had felt like a small, safe place.

“The women of Isle au Haut”¦ surely rescued from disillusionment what was once idyllic in my mind,” Greenlaw writes. “The black mark that diminished the ‘islandness’ that was forever most coveted by me fades with every passing day as life truly goes on.”

The author also uses her sharp memoir skills to balance the story’s drama. She can shift from describing the isolation and beauty while cross-country skiing around the island in winter to the hassles of getting a herring-seining business going with two friends as everything goes wrong with lousy gear.

Many words could describe Lifesaving Lessons: courageous (for both Greenlaw and her daughter), shocking, heartfelt, horrific, poignant and candid.

It’s important to know that Greenlaw’s daughter wanted this story, with its rawness, told through this book, “to inspire or give strength to some other young victim to break out of the cycle of abuse.”

It’s ultimately a story of healing and transformation, and, to Greenlaw’s credit, one without a trace of sappiness.

Linda Hedman Beyus is a Connecticut-based editor and writer.