“So we’re at the mercy of a ghost.”
Let us put aside speculation, and confine ourselves to the facts.
On Monday, the unresting spirit of Quentin Collins directed young David to remove a small vial of strychnine from his rolltop desk. The next day, an unseen spirit entered the cottage of Christopher Jennings, uncorked his whiskey decanter, and decanted several tablespoons worth of strychnine into it. Chris helped himself to a glass, and now he’s flat on his back, thinking things over.
At Collinwood, Julia’s sleep was interrupted by the ghost of a sobbing woman, who led her downstairs and out the front door. Picking up Barnabas along the way, Julia followed the ghost, who led them to the scene of the crime.
Now, I’m fairly certain that we know whodunnit — it was the muttonchops that walk like a man, last spotted fleeing the scene and shouting, “You’ll never catch me alive!” The questions that we need to resolve are more along the lines of whythehelldunnit.
#1. Why did Beth go to Julia, rather than anyone else?
#2. Why is Beth suddenly trying to stop Quentin’s plan?
#3. Why does Quentin want to kill Chris?
There are solutions to all of these mysteries, which regular readers should be able to work out for themselves, without resorting to time travel by way of the DVD box set. Don’t bother with the head canon; all the evidence that we need is right here in this room. As the man said, You know my methods, Watson. Apply them.