Lewis has studied serial killers for the past twenty-five years. With her collaborator, the neurologist Jonathan Pincus, she has published a great many research papers, showing that serial killers tend to suffer from predictable patterns of psychological, physical, and neurological dysfunction: that they were almost all the victims of harrowing physical and sexual abuse as children, and that almost all of them have suffered some kind of brain injury or mental illness. In 1998, she published a memoir of her life and work entitled “Guilty by Reason of Insanity.” She was the last person to visit Ted Bundy before he went to the electric chair. Few people in the world have spent as much time thinking about serial killers as Dorothy Lewis, so when her friend Betty told her that she needed to see “Frozen” it struck her as a busman’s holiday.

But the calls kept coming. “Frozen” was winning raves on Broadway, and it had been nominated for a Tony. Whenever someone who knew Dorothy Lewis saw it, they would tell her that she really ought to see it, too. In June, she got a call from a woman at the theatre where “Frozen” was playing. “She said she’d heard that I work in this field, and that I see murderers, and she was wondering if I would do a talk-back after the show,” Lewis said. “I had done that once before, and it was a delight, so I said sure. And I said, would you please send me the script, because I wanted to read the play.”