One day in 1980, when April Balascio was 11 years old, her father, Edward Wayne Edwards, woke up the household and told his wife and kids to start packing. They were leaving Watertown, Wisconsin, where they’d lived for about a year — and they were leaving immediately.

The scenario wasn’t unfamiliar: The Edwards family was nomadic, roaming from town to town every six months to a year, at their father’s whim, and often without warning.

“He’d tell us the we had to move in secret because he was protecting us, because there were people who wanted to hurt him or us,...