Christine Papin (Sylvie Testud), and Léa Papin (Julie-Marie Parmentier) are sisters with a troubled past, who work as maids in Le Mans, France. After a string of domestic jobs, they start working for the Lancelin family, which consists of Monsieur Lancelin, his wife and their adult daughter Genevieve. Christine sees in Madame Lancelin a mother figure, in spite of her severity. But their wretched background — an indifferent mother, a drunken, abusive father and time spent in orphanages — casts a shadow over the girls. Over time, their ill-fated situation darkens and they withdraw into themselves. Finally, after six years of service, they end up committing a particularly brutal crime on February 2, 1933: killing Madame Lancelin and her daughter after gouging their eyes out.