Chris Jennings turns into a werewolf when the moon is full, which it is about half the time in the universe of Dark Shadows. Old world gentleman Barnabas Collins has learned of Chris’ plight and decided to help him. As they make their way through an old cemetery to the hidden chamber where Barnabas will lock Chris up so that he doesn’t hurt anyone tonight, Barnabas asks Chris to confirm that he doesn’t remember anything he does in his lupine form. Chris does, saying that waking up and not knowing what he did the night before “is the most agonizing part of the whole thing.” You might think that he would find it even more agonizing to know that he has been killing one or two random human beings a month for the last seven years, but different things bother different people.
Chris asks how Barnabas knew that he didn’t remember what he did as the werewolf. Barnabas replies “Well, it’s obvious you’ve forgotten that you attacked me in this graveyard the night before last.” Chris says that “It’s a wonder you’re still alive.” To which Barnabas replies “No, it’s a wonder YOU’RE still alive!” For a moment we wonder how long this will go on, but Barnabas explains that werewolves can be killed by silver weapons. The head of the cane he carries is silver, and he struck him with it.
Barnabas shows Chris to the hidden room in the back of the old Collins family mausoleum. Barnabas himself was kept in a chained coffin in this room for over 170 years, when he was a vampire. He tells Chris that the room was originally constructed to hide ammunition from the British during the Revolution, which we have heard before. The coffin is still there; he tells him it is empty, and denies knowing anything about it. He says that the walls of the tomb are solid granite a foot thick; this is the first we’ve heard this detail. When Chris asks if anyone else knows about the room, Barnabas concedes that “A few” do. He assures him that none of them will be around tonight. Regular viewers will start making up a list of all the characters currently on the show who know about the room; Barnabas’s friend Julia Hoffman and his servant Willie Loomis know about it, as does strange and troubled boy David Collins. Barnabas can tell Julia and Willie to stay clear, and David has no reason to come to the cemetery tonight.
Barnabas explains that he will not show Chris the mechanism that unlocks the door from the inside, but promises to come back to release him after dawn. Chris urges Barnabas to leave at once; Barnabas insists on sticking around and asking more questions, saying that the moon isn’t up yet. Chris tells him that he first transformed shortly after he graduated from architecture school. “Oh, I was going to be an architect to be reckoned with, bold, imaginative, revolutionary. I thought nothing could stand in my way. Then something did.”
After Chris delivers a monologue about what a soulful and remorseful serial killer he is, Barnabas finally does close the secret panel. He sticks around until he hears the sounds of the werewolf snarling in the hidden room.
Chris’ nine year old sister Amy is staying at the great house of Collinwood. David finds her standing outside the front door, staring at the moon. She tells him that the moon scares her sometimes. His response is “Well, then don’t look at it,” which does seem logical. But she tells him that she can’t help it. David complains about how odd she is. We will hear more of this grumbling; it makes them seem like an old married couple, and is hilarious.
Amy and David are coming under the influence of the evil spirit of the late Quentin Collins. Quentin keeps trying to get them to set various members of the Collins family up for lethal traps; they haven’t succeeded yet in killing anyone, but housekeeper Mrs Johnson has caught on that there is something peculiar going on with the two of them, and she is frightened.
Mrs Johnson enters the drawing room to do some straightening up and finds the children playing a game with a deck of stage magician’s oversized cards. She and they stare silently at each other for a minute or two, and she protests. They say they were just watching her work, and she orders them to go to bed. They object that it isn’t bedtime yet. Of course it isn’t, Mrs Johnson doesn’t work around the clock. They get even more intensely on her nerves by bringing up a recent incident when she saw Quentin’s ghost, and in her exasperation she chases them out of the room.

There isn’t anything about Quentin in the episode prior to that scene, so I cannot imagine what viewers would make of it. It’s late in the day, a domestic is tired, and a couple of kids are trying to annoy her. That is a relatable situation, but it doesn’t match with the heavy, melodramatic Dark Shadows music and the terrified affect with which Clarice Blackburn plays Mrs Johnson. I suppose that by January 1969, Dark Shadows was so widely known as a supernatural thriller that most people tuning in for the first time would assume that something paranormal was going on, but if they turned the television on after the opening titles and didn’t realize what show they were watching, they could only have concluded that they were witnessing an utterly ludicrous case of exaggerated seriousness. After David and Amy are out of Mrs Johnson’s sight, we see them go upstairs laughing, but that proves only that they are trying to upset her, not that they are connected to a malign power greater than themselves.
Barnabas enters and sees that Mrs Johnson is upset. She begins to tell him why, but interrupts herself to declare that he won’t believe her. He assures her that he will, and keeps asking her to go on. After she has told him everything she and the audience both know, he asks her to start over. The scene cuts out, suggesting that Barnabas is taking pains to get as much information from Mrs Johnson as he possibly can.
The children go to the little room in the long-deserted west wing of the house where they first met Quentin. Quentin is there when they arrive. This is the first time we have seen Quentin waiting for them; previously, they have had to summon him. Quentin does not speak; David can sense that he wants Amy to go back to the main part of the house so that they can talk privately.
Alone with Quentin, David asks where “the bottle” is. Quentin opens a rolltop desk, and David sees a bottle. He is shocked to find that the bottle is labeled “strychnine.” He declares that he won’t hurt Chris, and he runs out of the room.
Downstairs, Amy is in the drawing room, where she presses a few keys of the piano. We heard her play “London Bridge” in #656, but this doesn’t seem to be a part of any song. She is just idly pecking at the keyboard. When David comes, Amy complains about how long he was gone. He is distant, refusing to maintain eye contact or to answer any of her questions. He says they won’t be playing tonight.
We cut back upstairs, where Quentin is picking up the bottle of strychnine. Mrs Johnson saw Quentin in Chris’ cottage, so we know that he can go there. If David won’t poison Chris, perhaps Quentin will do it himself.