A soldier who died in World War I. A photographer who, over a hundred years later, finds his autographed diary and decides to follow its trail from Avellino in southern Italy to the hills of the Karst in the northeast. Both have the same name: Eugenio Barzaghi. The only possible point of their encounter is the “Bocca d'inferno” (Mouth of Hell): a trench with a frightening name where the soldier fought.