River Donaghey grew up in a cult. Or at least that’s what some people called it. His parents called it a “personal-growth seminar group.” Its leader called it “one big happy family.” But there was a dark side to the world River grew up in. One he never heard about as a kid.

In the 1970s and 80s, a self-help company called Lifespring took America by storm. Hundreds of thousands of people walked out of Lifespring as true believers, convinced that the seminars had the power to change the world. But dozens of trainees claimed that after taking a seminar, they had a psychotic break. Some spent months in the hospital. Others attempted suicide. And at least four people died.

River spent the past year digging into the bizarre, untold story of Lifespring and its controversial leader: a convicted felon turned New Age guru named John Hanley. What he uncovered made him question everything he thought he knew about his childhood. And about the seminars that are still changing lives—and ruining them—to this day.