The protagonist is a woman who has been thrown out into the street without any money by her jealous husband, when he discovers she has been carrying on an affair. She is not even allowed to see their young son. She sinks into depravity.

Twenty years later, she has become the mistress of a criminal. When he finds out that her husband is now the Attorney General, her lover decides to blackmail him. Desperate to shield her son from her disgrace, she shoots and kills her lover.

By chance, the lawyer assigned to her turns out to be her own son, on his first case. He is puzzled and frustrated when she refuses to defend herself in court, or even to provide her name (which forces the tribunal to identify her as "Madame X"). During the trial, her husband shows up in support of his son. When the defendant sees that her husband recognizes her and is about to speak out, she makes an impassioned plea, not for mercy but for understanding of what drove her to murder. As she had intended, the hidden message silences her husband. When she faints from the strain, she is carried into a private chamber. There, she kisses her still-unaware son and dies.

• Madame X (1910 play) an English adaptation by John Raphael
• Madame X (1916 film) starring Dorothy Donnelly
• Madame X (1920 film) starring Pauline Frederick
• Madame X (1929 film) starring Ruth Chatterton
• Madame X (1937 film) starring Gladys George
• Madam X (1952 film) starring Gloria Romero
• Madame X (1954 film)
• Madame X (1966 film) starring Lana Turner
• Madame X (1981 film) starring Tuesday Weld
• The Trial of Madame X, a 1948 film, based on the same story as the other Madame X films
• J.W. McConaughy (1910) Madame X, Grossett & Dunlap, New York, a novel based on the play by Alexandre Bisson Front Cover Illustration by Edward Charles Volkert