The lesson we learn from this book is: If, every time a certain gentleman calls, and you invite him in for tea, he engages you in a hypnotic battle, otherwise known as a staring contest of evil. STOP INVITING HIM IN FOR TEA.

Also I'm fairly sure the recent Netflix series "Hemlock Grove" is at least loosely based on this book. Fun to read, but kind of ridiculous in its characters' insistence on propriety, even when their lives are obviously at stake.