It was an autumn evening in Boston, and the city was starting to settle into the stillness of the night. There was an eeriness in the air, heavy with the weight of centuries-old past mysteries. On this very evening, a curious group wandered through the narrow streets, soaked in the golden glow of flickering streetlamps, casting long shadows on the cobblestones. For once, even the bravest among them paused to look over their shoulders. No one knew for certain, but each felt a sensation of being watched and walked along. [...]