This fact-based film follows the infamous Papin sisters, Christine (Sylvie Testud) and Lea (Julie-Marie Parmentier), who lived in France in the 1930s. Christine is protective of Lea, a wide-eyed youngster. As Christine's relationship with her mother deteriorates completely, she goads Lea into shunning her mother as well. The pair eventually find work as maids and soon indulge in a passionate affair with each other that inevitably leads to murder.