Historian and novelist Rebecca Stott’s memoir, just published, describes how she grew up in a cult

As a girl in Brighton, England, the historian and novelist Rebecca Stott knew her upbringing was strict and different, but it was only later in life that she would say she was raised in a cult. Her father, Roger, had been an officer in the Exclusive Brethren, a radical Protestant sect that closely controlled the lives of its members.

“My family hadn’t belonged to the Brethren,” Ms. Stott writes in her new book, “we’d been caught up in them. Caught up like a coat catching on thorns. Caught up in a scandal. Caught up in the arms of the Lord. Whichever way you phrased it, it meant you didn’t get to choose, and that there was no getting away.”

Her father eventually left the group, and expressed great regrets at the end of his life about his role in enforcing the sect’s codes of behavior. With the help of rare pamphlets, diaries and other documents her father left her, Ms. Stott wrote a memoir and history, “In the Days of Rain: A Daughter, a Father, a Cult.” Below, she talks about the emotional drain of writing it, the “collective PTSD,” or post-traumatic stress disorder, that she found, and more.

When did you first get the idea to write this book?

When my father lay dying, he struggled to try to explain to me why in the ’60s things got so bad in the extreme religious group into which I had been born and he had been born before me. It was terribly sad, and I tried, with a tape recorder, to get him to explain what happened and why it was so distressing for him on his deathbed. He died before he could explain. I promised him, two or three days before he disappeared into the morphine, that I would do my best. The main question was: How had a good, decent group of people gotten caught up in a cult? How did they become compliant? ...

I thought all I had to do was study the paperwork, figure out what happened in what order, and then I would understand. What I didn’t anticipate was that there were so many holes in the story. It was more difficult because so much of it was personal, moving, difficult, really upsetting.