​In a grand estate far from the soot-stained air of the capital, there stood a manor of ancient stone—the ancestral seat of a Great Duke, passed down through many generations. Beyond its wrought-iron gates, the hallways were lined with dark mahogany and gold leaf, the air smelling of beeswax and heavy drapes. But beneath this veneer of aristocratic splendor, a cold secret was woven into the very fabric of the house. ​In a...