In this revelatory, authoritative portrait of Donald J. Trump and the toxic family that made him, Mary L. Trump, a trained clinical psychologist and Donald’s only niece, shines a bright light on the dark history of their family in order to explain how her uncle became the man who now threatens the world’s health, economic security, and social fabric.

Mary Trump spent much of her childhood in her grandparents’ large, imposing house in the heart of Queens, New York, where Donald and his four siblings grew up. She describes a nightmare of traumas, destructive relationships, and a tragic combination of neglect and abuse. She explains how specific events and general family patterns created the damaged man who occupied the Oval Office, including the strange and harmful relationship between Fred Trump and his two oldest sons, Fred Jr. and Donald.

A firsthand witness to countless holiday meals and interactions, Mary brings an incisive wit and unexpected humor to sometimes grim, often confounding family events. She recounts in unsparing detail everything from her uncle Donald’s place in the family spotlight and Ivana’s penchant for regifting to her grandmother’s frequent injuries and illnesses and the appalling way Donald, Fred Trump’s favorite son, dismissed and derided him when he began to succumb to Alzheimer’s.

Numerous pundits, armchair psychologists, and journalists have sought to parse Donald J. Trump’s lethal flaws. Mary L. Trump has the education, insight, and intimate familiarity needed to reveal what makes Donald, and the rest of her clan, tick. She alone can recount this fascinating, unnerving saga, not just because of her insider’s perspective but also because she is the only Trump willing to tell the truth about one of the world’s most powerful and dysfunctional families.