Based on the true story of two chambermaids (the Papin sisters) of 1930s France who murdered their employer and her daughter. Christine Papin (Sylvie Testud), and Lea Papin (Julie-Marie Parmentier) are sisters with an already troubled past. Madame Lancelin takes them into her home and employs the girls as maids. Christine sees in Madame Lancelin an ideal mother figure — in spite of her severity. But their wretched background — an indifferent mother and drunken abusive father — casts a shadow over the girls and over time their ill-fated situation darkens. The sisters withdraw into themselves and finish by committing the worst — killing Madame Lancelin and her daughter after six years of service, on the 2 February 1933 in Le Mans.