First off, here's the original trailer for the film:
While we'll never know how Karloff may have fared as Jonathan in the film version, we can get a sense of how his performance came across through this radio play version of the story broadcast by NBC in the fifties:
Here's the presentation we mentioned during the episode, offering a psychoanalysis of the Brewster family:
And here's an article discussing the true case that may have inspired Joseph Kesselring when he wrote the original play:
Enjoy and thanks for listening!