I would be very surprised if any of the grown-ups figured out what was going on this early. There's no reason for Roger to associate the tripwire with supernatural causes. And they have no idea of what the children have been up to, so they haven't much evidence to help them.
Cavada Humphrey did an absolutely fabulous voiceover. I'd love to hear her read a ghost story. Also I was thinking, as Madam Findley went into her trance, that she would have made an interesting Julia Hoffman if Grayson Hall hadn't been available.
Amy's a strange child. She doesn't seem to be at all bothered by the fact that she and David caused Roger to fall down the stairs. Apparently David broke free of Quentin when he saw his father's accident, but Amy went back to Quentin's room for more fun and games. I'm not sure what is going on with her. Is it enchantment, or possession, or simple devotion to an adult figure - even if it's a ghost - who pays attention to her?
Did that Tarot card say LAX? If so, does that meant that Roger will be going to Los Angeles instead of London? And is there a skyscraper in Los Angeles that would make an appropriate Tower of Destruction?