Piedmont, late nineteenth century. Cino, nine years old, lives in Cuneo with his poor mountaineers parents; he is entrusted to a shady French carter to be conducted in France and “rented” to work in the summer pastures of Mercantour. During the trip, Cino befriends Catlin, a girl of his age, who along the way gets ill with pneumonia and is abandoned by the carter. Arriving in France, Cino gets mistreated by his master, and soon attempts a desperate escape, which leads him to meet again Catlin. The two decide to walk across the Alps to back down in Piedmont and go home. The route to Italy reveals itself fraught with surprises and dangers, as the mountain, populated by mysterious and hostile forces, seems to have a magical influence on Catlin.