Educated. By Tara Westover. Random House; 385 pages; $28. Hutchinson; £14.99.

IN A lecture during her first semester at Brigham Young University, a Mormon college in Utah, Tara Westover encountered an unfamiliar term. “I don’t know this word,” she told her professor. “What does it mean?” He snapped at her angrily—but Ms Westover was not making a tasteless joke. She had never been taught about the Holocaust. Nor had she learned about the civil-rights movement, or physics or any geography beyond the mountains and valleys that surrounded her family home in rural Idaho. That semester was the first time she had ever set foot in a proper classroom. She was 17.

Ms Westover was the youngest of seven children raised by Mormon survivalists in a town of 234 people. Like her siblings, she was kept out of school, which her father regarded as “a ploy by the government to lead children away from God”. Her early education consisted largely of helping him sort metal scraps in the family junkyard, and watching her mother concoct herbal remedies for headaches, burns and cancer—required because the family also avoided doctors. Even when her siblings were maimed, their skin charred by blowtorches or brains injured in car crashes, they were treated with their mother’s homeopathic mixtures.

In “Educated”, her riveting memoir, Ms Westover brings readers deep into this world, a milieu usually hidden from outsiders. Scarred by the Ruby Ridge incident of 1992, in which several members of an Idaho family were fatally shot by federal agents after resisting arrest, her father became convinced the feds would ultimately come for his clan, too. He loathed the idea of “registering” with the government, so did not obtain birth certificates for Ms Westover and three other children. He spent his meagre income from scrap metal on a cache of huge guns and a giant gasoline tank, for fighting or fleeing when the authorities showed up. Ms Westover slept with a “head-for-the-hills” bag by her bed.

As she entered adolescence, she writes, one of her brothers grew frighteningly violent. He would drag her to the bathroom by her hair and slam her head into the toilet. Her parents mostly ignored it. They even tried to convince Ms Westover that she was imagining things, and that she was the devilish party. When another brother left the compound to attend college, Ms Westover was inspired to emulate him. She taught herself enough algebra and grammar to pass Brigham Young’s exam and enrolled in 2004.

At first she floundered, academically and socially. How could people call themselves Mormon and drink Diet Coke—or wear skirts that revealed their knees? But in time she excelled, winning a fellowship to study at Cambridge, where she immersed herself in history and philosophy. Then she did a doctorate at Harvard.

Her story is remarkable, as each extreme anecdote described in tidy prose attests. That someone who grew up in her circumstances could achieve as much as she has is astonishing. All the same, readers who enjoyed more mundane backgrounds will empathise. The central tension she wrestles with throughout her book is how to be true to herself without alienating her family. Her upbringing was extraordinary, but that struggle is not.