Act I

Wendla Bergmann, an adolescent girl in late-19th century Germany, laments that her mother gave her "no way to handle things" and has not taught her the lessons she needs to learn ("Mama Who Bore Me"). She tells her mother that it is time she know where babies come from, considering that she is about to be an aunt for the second time, but her mother cannot bring herself to explain it to Wendla. The other young girls in town appear to be similarly innocent ("Mama Who Bore Me (Reprise)").

At school, some teenage boys are studying Virgil in Latin class. When Moritz Stiefel, a very nervous and intense young man, misquotes a line, the teacher chastises him harshly. Moritz's best friend, the handsome and self-assured Melchior Gabor, tries to defend him, but the teacher will have none of it, and hits Melchior with a stick. Melchior reflects on the shallow narrow-mindedness of school and society, and expresses his intent to change things ("All That's Known").

Moritz tells Melchior about some dreams that have been keeping him up at night; as he describes them, Melchior realizes that the dreams are of an erotic nature. Moritz is in a panic and does not understand what he sees in his dreams, but Melchior is much more savvy and agrees to explain it all to Moritz in the form of an essay, complete with pictures. All the boys sing about their own frustrating thoughts and desires in a rock and roll fashion ("The Bitch Of Living").

Some girls are gathered together after school and tease each other as they fantasize about marrying the boys in the town -- at the top of the list is the radical, intelligent, and good-looking Melchior. Meanwhile, upstage, the gay student Hanschen masturbates as he looks at an erotic postcard; further upstage, the piano student Georg indulges in some lively fantasies about his well-endowed female piano teacher ("My Junk").

Moritz has eagerly digested the essay that Melchior prepared for him, but complains that his new knowledge has only made his dreams even more vivid and torturous. Melchior tries to calm and comfort his friend, but Moritz runs off in frustration. In a stylized musical number, all of the boys and girls express their desire for physical intimacy ("Touch Me").

Wendla stumbles upon Melchior while walking through the woods. He explains that he's at his special spot, where he likes to read and work on his journal, and invites Wendla to lie down next to him. Each of them considers what it would be like to give in to their physical desires, but they do not do so ("The Word Of Your Body"). Meanwhile, at school, Moritz is thrilled to learn that he has passed his midterm examination, but the teacher and schoolmaster do not like Moritz and decide that they will make sure that he fails his final exam.

Martha, one of the teenage girls, accidentally admits to her friends that her father abuses her physically (including, as the audience learns, sexual abuse) and that her mother allows it to happen. The other girls are horrified to hear this, but Martha makes them promise not to tell anyone, lest she end up like Ilse, a friend from childhood who now wanders homeless and aimless because her parents kicked her out of their house ("The Dark I Know Well"). Later, Wendla finds Melchior again at his spot in the woods, and tells him that one of her friends regularly gets abused by her father. Melchior is appalled to hear this, but Wendla tells him she's never been beaten and wants Melchior to hit her with a stick so that she can learn what it's like. Melchior at first refuses this shocking request, but she eventually persuades him, and he hits her and throws her to the ground. Melchior runs off, disgusted with himself, as Wendla lies on the ground and sobs. Alone, she looks up and realizes Melchior has left his journal on the ground. She picks it up and takes it with her.

Moritz has failed his final examination, and his father reacts with disdain and contempt when Moritz tells him that he has failed out of school. He writes to Melchior's mother for money to flee to America; she tenderly but firmly denies his request, but promises to write his parents to discourage them from being too hard on him ("And Then There Were None").

In a stuffy hayloft during a storm, Melchior considers his own frustration at being caught between childhood and adulthood ("The Mirror-Blue Night"). Wendla finds him once again, telling him she wants to return his journal, and each one awkwardly apologizes for what happened the last time they met. Before long, they begin to kiss; Wendla resists his advances at first, but soon gives in to Melchior. Though she still seems uncertain about how far she wants to take their physical relationship, they begin to have sex as the lights go down ("I Believe").

Act II

Wendla and Melchior are finishing up their moment of intimacy in the hayloft; they reflect on and discuss what has just happened ("The Guilty Ones"). Meanwhile, Moritz, having been thrown out of his home, wanders the town at dusk, carrying a pistol("Don't Do Sadness"). He happens upon Ilse, also homeless, who invites him to join her in sharing some old childhood memories, and perhaps something more, but Moritz refuses ("Blue Wind"). After she has left, he calls after her, but it is too late; she is gone. Believing that he has nowhere to turn, Moritz shoots and kills himself.

At Moritz's funeral, each of his friends drops a flower into his grave, and Melchior chastises Moritz's father for being so cruel to his friend, as the other students look at Moritz's father with disgust for pushing Moritz too hard when he was alive ("Left Behind"). Back at school, the schoolmaster and teacher inform Melchior that Moritz's parents found the sex essay he had written for him. They lay the blame on Melchior for his friend's suicide, and although Melchior knows that he is not to blame, he knows there is nothing he can do to fight them ("Totally Fucked").

Elsewhere that night Hanschen meets up with his shy and delicate classmate Ernst. In a comedy-relief scene, Hanschen shares his pragmatic outlook on life with his classmate before seducing him. It is Ernst's first sexual experience, and he tells Hanschen that he loves him as the two share a passionate kiss ("The Word Of Your Body (Reprise)").

Wendla has become ill, and her mother takes her to visit a doctor He gives her some medication and assures them both that Wendla is suffering from anemia and will be fine, but he takes Wendla's mother aside and tells her that Wendla is pregnant. When her mother confronts her with this information, Wendla is completely shocked, not understanding how this could have happened. She soon realizes, however, how it must have happened, finally solving the mystery that her mother refused to clear up for her at the start of the show. Though she chastises her mother for being at fault for leaving her ignorant, her mother will have none of it and insists Wendla tell her who the father is. Wendla reluctantly surrenders a passionate note Melchior sent her after they consummated their relationship.

Wendla reflects somberly on her current condition and the circumstances that led her to this difficult spot, but in the end she remains optimistic about the arrival of her future child ("Whispering"). Meanwhile, Melchior's parents argue about their son's fate; his mother does not believe that the essay he wrote for Moritz is sufficient reason to send him away to reform school. When Melchior's father tells his wife about Wendla's pregnancy, however, she agrees that they must send Melchior away, which they do without telling him that Wendla is expecting a child.

At the reform school, Melchior gets into a fight with some boys, who grab a letter he has just received from Wendla and use it in a masturbation game. As one of the boys reads from the letter, Melchior finally learns about Wendla and their child, and he escapes from the institution to find her. He does not know that he is too late: Wendla's mother has already taken her to an underground practitioner to have an abortion. When Melchior reaches town, he stumbles across Moritz's grave, and promises to himself that he and Wendla will do a better job raising their child in a compassionate and open environment.

Melchior spots a freshly dug grave and, upon reading the marker, discovers that Wendla has died from 'anemia.' Overcome with grief, Melchior takes out a razor with the intention of killing himself. Just then, his fallen friend, Moritz, and lover, Wendla, join him onstage in the form of ghosts in his mind to offer him their strength from beyond the grave. As if singing directly to him, they persuade him to journey on, and he resolves to live and to carry their memories with him forever ("Those You've Known").

Led by Ilse, the entire cast assembles onstage to sing one final song of life and hope ("The Song of Purple Summer").