Sherlock Holmes and Dr. Watson respond to a country physician's plea about a reputed ancestral curse after a mysterious death on a bleak moor; with one heir returning to a sprawling estate, Holmes sends Watson to observe daily life, strange lights, and local eccentricities. The narrative balances gothic atmosphere and methodical detection as Watson's field reports and Holmes's deductions unravel human motives, expose an elaborate deception that exploited superstition, and reveal a rational explanation for the terrifying events.