Le Vallon Aérien Ou, Relation du voyage d'un aéronaute dans un pays inconnu jusqu'à présent; suivie de l'histoire de ses habitans et de la description de leurs moeurs

At a time when balloon flights were mostly spectacles, a diligent aeronaut named de Montagnac devoted himself to serious scientific observation. Over eight years he drifted above the Pyrenees, sketching peaks, measuring temperature, and charting winds that few had ever recorded. His meticulous notes promise a fresh perspective on the high mountains, but his greatest ambition lies beyond the known summits.

During a later ascent he spotted a perfect circle of peaks surrounding a vast, hidden plain, a place locals called the Vallon Aérien. Guided to the foothills by summer shepherds, he learned that the valley is cut off by sheer cliffs and is said to shelter a community rumored to practice strange arts. The narrative follows his attempts to enter this secluded world and to describe the customs, language, and daily life of its enigmatic residents.