The Animal Tamer invites the audience to visit his menagerie—featuring “the serpent Lulu.”
Lulu is sitting for her portrait, observed by Dr. Schön, a wealthy newspaper publisher and her long-time lover. Alone with Lulu, the Painter tries to seduce her. Just then her husband, the Physician, forces his way into the room and collapses in shock from a heart attack. Lulu, seemingly unmoved, realizes she is a rich widow, while the Painter wonders what will happen to her.
Lulu and the Painter have married. She is surprised to learn that Schön—who years earlier had found her on the streets, given her an education, and then made her his mistress—has become engaged. Schigolch, an old man and friend of Lulu’s who may be her father or a former lover, pays her a visit and she gives him money. Schön now wants Lulu out of his life so that he can marry. He reveals the story of her past to the Painter, who is so horrified by it that he cuts his throat. Schön is shocked by Lulu’s cold reaction but she, dismissing his protestations, replies that he will eventually marry her anyway.
Weeks later, Lulu is appearing in a ballet composed by Schön’s son, Alwa. In her dressing room, she tells Alwa of her latest admirer, the Prince. After she has gone on stage, the Prince talks to Alwa of his love for Lulu. Suddenly she storms back in: she has seen Schön in the audience with his fiancée and refuses to dance for her. Schön soon follows and demands to be left alone with Lulu. He asks her not to stop his marriage, but when she mentions her plans to marry the Prince, he realizes that he is incapable of letting her go. At Lulu’s dictation, he writes a letter to his fiancée to break off the engagement.
Schön and Lulu, now married, live in a luxurious home, but she continues to attract admirers, among them the lesbian Countess Geschwitz. Schön is distraught that such people are now part of his life. The Countess, Schigolch, an Acrobat, and a Schoolboy gather at the Schön house and all three men declare their love to Lulu. Alwa appears and, thinking himself alone with Lulu, also declares his love. Schön, who has observed the scene, drives his son away, then hands Lulu a revolver, demanding that she shoot herself to protect his reputation. Lulu justifies herself by saying that she has never pretended to be anything but what she is. Schön forces her to her knees but is distracted by the Schoolboy’s cries for help. Lulu fires five shots into her husband’s back and begs the returning Alwa not to turn her over to the police.
An orchestral interlude depicts Lulu’s arrest, murder trial, imprisonment, illness with cholera, commitment to the hospital, and the plans for her escape: the Countess, who has allowed herself to be infected with the same disease, is to take Lulu’s place in the hospital.
Alwa, together with the Countess and the Acrobat, awaits Lulu’s return in Schön’s former apartment. When she arrives on Schigolch’s arm, the Acrobat is appalled by her wasted appearance and leaves, threatening to betray her to the police. Alone with Lulu, Alwa again proclaims his love and agrees to go to Paris with her.
A crowd has assembled in Alwa’s Paris mansion in honor of Lulu’s birthday. A number of the company have invested in a new cable railway and question the Banker about their prospects. The Marquis, threatening to reveal Lulu to the police as Schön’s murderer, tries to blackmail her into working in a brothel, but she defies him. The Acrobat also tries to blackmail Lulu, then Schigolch appears, asking her for money. Lulu breaks into tears. Together with Schigolch, she plots to dispose of the Acrobat by having him killed. There is uproar as the news spreads that the railway shares have collapsed—everyone is ruined. In the confusion Lulu escapes, just as the Marquis arrives with the police.
In a shabby garret in London, Alwa, now syphilitic and a derelict, and Schigolch await Lulu’s return from her first night as a prostitute. She arrives with a client, the Professor, who remains silent throughout the proceedings. As he leaves the now destitute Countess appears, bringing with her Lulu’s portrait. Lulu and her three admirers contemplate its beauty and how their fate has been bound up with it. Lulu goes into the street again, followed by the Countess, while Alwa reflects on the mess he has made of his life. Lulu returns with another client, an African Prince. In a clumsy attempt to protect her, Alwa attacks him and is killed by him. In despair, Lulu rushes out into the street again. Schigolch drags Alwa’s body away and disappears. The Countess returns. Gazing at the portrait, she considers suicide when Lulu arrives with yet another customer, Jack the Ripper. They argue about money, then go into her room. Suddenly Lulu is heard screaming—Jack has killed her. The Countess tries to help but Jack stabs her as well. He leaves as the dying Countess cries out for Lulu.