This penultimate episode falls flat on every facet: from the acting, dialogue, and story progression.
The hidden tunnel wrinkle from the previous episode doesn't get explored, as inexplicable as that may seem. The homeowners just accept it as part of the house and move on to other unproven leads.
The characters of Theodora Birch, Roger Kaplan, John Graff, and the Winslow family has reached the apex of what I would consider insufferable. These characters are melodramatic and abhorrent. Their eccentricities do nothing to contribute to the mystery of the story - in fact it's rather pointless and distracting. They scream and yell at odd moments, go on long diatribes about tangentially unrelated topics like "The Fourth Turning" in the middle of a sentence, and generally gives you no reason for you to care for what they have to say or feel.
This series cannot end soon enough and at this point, I couldn't care less about what the ending is going to be in this adapted series that is "based on a true story".