The narrator, a Washington police superintendent, recounts an investigation of strange phenomena at a remote Appalachian summit known as the Great Eyrie: unexplained noises, vapors, flames and ash prompted local newspapers and growing alarm among nearby settlements. Observers note peculiar bird behavior and the mountain’s deep, inaccessible basin, raising fears of volcanic or subterranean activity that could endanger the region. Authorities and curious adventurers undertake efforts to approach and study the summit, including an attempted balloon ascent, while the account emphasizes the physical barriers and mounting urgency to determine the true nature of the mystery.