Set in the recent past, , the musical opens on a group of angry youths unhappily living in suburbia (identified as Jingletown, USA) and saturated with TV. Fed up with the state of the union, the company explodes in frustration American Idiot). The musical then focuses on three best friends: Johnny, Will, and Tunny. The three feel threatened by their mundane lives. Johnny goes to commiserate with Will Jesus of Suburbia. The appearance of a third friend, Tunny, spurs change when the three run out of beer. At the 7-Eleven, Tunny exposes the do-nothing go-nowhere quicksand of their lives City of the Damned. They get riled up, and Johnny challenges his friends to engage I Don't Care. Will's girlfriend Heather appears. She is pregnant and doesn't know what to do Dearly Beloved. Johnny borrows money from his mother and buys bus tickets to the city for himself and his friends. Heather reveals to Will that he is going to be a father, so he decides to stay home Tales of Another Broken Home. Johnny and Tunny depart for the city with a group of other jaded youths Holiday.
While Johnny wanders the city and pines for a woman he sees in an apartment window Boulevard of Broken Dreams, Tunny finds it hard to adjust to urban life and is seduced by a television ad for the army Favorite Son. Tunny realizes that his generation has been so numbed and apathetic that nothing, not even the bright lights of the city, will excite him Are We the Waiting. He enlists in the army.
Frustrated by his friend's departure and his inability to find girls or fun, Johnny conjures a rebellious powerful reflection of himself called "St. Jimmy" and shoots heroin for the first time St. Jimmy. Back in Jingletown, Will sits on the couch as his girlfriend's pregnancy progresses. He drinks beer and begs for a release. Meanwhile, Tunny is deployed to a war zone, and is soon shot and wounded Give Me Novacaine.
Johnny finds that St. Jimmy has given him everything he's ever wanted—girls and fun—and spends the night with the girl he saw in the window, whom he calls "Whatsername". Johnny is smitten with Whatsername and wants to celebrate, but St. Jimmy has other plans for them Last of the American Girls/She's a Rebel. Johnny and Whatsername go to a club, shoot drugs together, and have passionate sex. By this time, Will and Heather's baby girl has been born, and Will is increasingly oblivious as Heather tenderly commits herself to her baby's future Last Night on Earth.
Heather has had enough of Will's pot-and-alcohol-fueled apathy. Despite Will's protestations, she takes the baby and walks out Too Much, Too Soon. Around the same time, lying in a bed in an army hospital Before the Lobotomy, Tunny falls victim to the hopelessness he has seen during wartime and hallucinates. He and his nurse engage in a balletic aerial dance Extraordinary Girl. He quickly falls in love with her.
Back in the city, Jimmy reappears but Johnny ignores him, watching Whatsername sleep. Johnny muses on their relationship and reveals the depth of his love for her When It's Time. The temptation of drugs, however, is too great; Jimmy forces Johnny to become increasingly erratic, and he eventually threatens Whatsername (and then himself) with a knife Know Your Enemy. Whatsername attempts to talk about his behavior, but is shocked at the depths to which he has spun out of control. Meanwhile, the Extraordinary Girl dresses Tunny's wounds and Will sits on the couch, once again alone 21 Guns. After this, Johnny and Jimmy leave and Johnny leaves a note for Whatsername, saying that he has chosen Jimmy and his drugs over her. Frightened and fed up, Whatsername explodes at Johnny, telling him that he is not the "Jesus of Suburbia" and revealing to him that St. Jimmy is nothing more than "a figment of [his] father's rage and [his] mother's love" Letterbomb. She leaves him.
Hurt by Whatsername's departure, Johnny is forced to admit that his life has amounted to nothing; he longs for better days ahead, Tunny longs for home, and Will longs for all the things he's lost Wake Me Up When September Ends. St. Jimmy appears and makes one last attempt to get Johnny's attention, but that part of Johnny has died, resulting in the metaphorical suicide of St. Jimmy The Death of St. Jimmy. Johnny cleans up and gets a desk job but soon realizes that he can find no place for him in the city East 12th Street. Will, all alone with his television, bemoans his outcast state Nobody Likes You. As he finally gets up off the couch, Heather appears with her new show-off rockstar boyfriend Rock and Roll Girlfriend. Will heads to the 7-Eleven to get away from them and, surprisingly, finds Johnny there. Johnny had sold his guitar for a bus ticket home. Tunny returns from the war zone (as an amputee) with the Extraordinary Girl. As Tunny introduces his friends to the Extraordinary Girl, Johnny becomes furious with him for leaving the group, but forgives him and the three friends embrace. Heather and her boyfriend arrive. In an uneasy truce, she gives the baby to Will. Other friends show up to greet the three men they haven't seen in a year We're Coming Home Again. One year later, Johnny laments that he lost the love of his life, but he accepts that he can live inside the struggle between rage and love that has defined his life. With this acceptance comes the possibility of hope Whatsername.
After the cast takes their bows, the curtain rises to reveal the entire company with guitars, with which they perform the song, "Good Riddance (Time of Your Life)".