Henry Dunant, son of a Geneva francophone upper class bourgeoisie family, works for a Swiss exploitation company in French Algeria; when the colonists are thirsty, he returns determined to convince the firm and emperor Napoleon III to build a dam for them. After his Uncle, Dr. Hubert Dunant, diagnoses him not with Algerian typhus, just malaria, also his first meeting -dropping drawers in hospital for a shot- with nurse Cécile Thuillier, and meeting his careerist brother Daniel's fiancée, Léonie Bourg-Thibourg, daughter of the firm's boss, the board approves his plan. On his way to the emperor, who didn't even concede to receive him, Henry gets stuck in Castiglione, part of the Austrian province Lombardy which French troops came to 'liberate'; his Geneva friend Dr. Louis Appia saves his life by presenting him to suspicious Austrian troops as his medical assistant...
