Paris in 1871. The government army, defeated in the war with Prussia, split into two warring camps, and the national guards seized power in the city. The family of Parisian architect Émile Saint-Clair, returning to the capital from the province, finds themselves at the epicenter of a bloody confrontation. Bursting into Émile's home, robbers brutally kill the elderly nanny Marie-Jeanne and abduct eleven-year-old Hélène. The parents are in despair, but they do not yet know what courageous and resilient heart their middle daughter possesses and what cruel trials await her.