Emma left on a Friday morning with a stuffed duffel bag and a quick hug.

“My dad’s going to stay a few nights,” she said while she checked her phone. “Just to make sure the apartment’s okay while I’m gone. He’s kind of intense, but he won’t bother you. Just… be polite.”

I nodded and didn’t think much of it. We had shared the small two-bedroom for almost a year. Her dad was just a name I had heard on phone calls. Then the doorbell rang at 6:40 p.m. and I opened it to find a man who filled the entire frame.

Harlan Cole was forty-seven, broad-shouldered, and taller than...