As Richard Dadier, a soft-spoken ex-serviceman, accepts his first teaching job in a tough New York City high school, he asks his new principal, Mr. Warnecke, about the school's discipline problem and is assured that at North Manual High, "there is no discipline problem." The other teachers, particularly the cynical Jim Murdock, who calls the all-male school a "garbage can" and cautions Dadier not to turn his back on the students, do not lessen his anxiety. That evening, Dadier celebrates his new job with his wife Anne, who, although deeply in love with her husband, worries not only that her pregnancy will make her unattractive to him, but that she will miscarry as she had once before. Dadier's first day teaching English is discouraging. The pupils, mostly lower-class juvenile delinquents, ignore his requests and call him "Daddy-O," and when he asks Gregory W. Miller, a bright but alienated black student, to use his leadership abilities to promote cooperation in the classroom, the young man just shakes his head. That afternoon, Lois Judby Hammond, another new teacher who seems attracted to Dadier, is nearly raped by one of the students. Dadier severely beats the boy, and the next day, the students greet him with threatening glares and angry silence. After work, Dadier accompanies Joshua Y. Edwards, a new math teacher who passionately loves jazz and swing, to a bar, where they have a drink too many and bemoan the students' hostility. While cutting through an alley to the bus stop, both teachers are brutally beaten by Dadier's student Artie West and his gang of hoodlums. Anne urges Dadier to leave the school, but he declares, "I've been beaten up, but I'm not beaten." While recuperating, Dadier visits his former professor, who assures him that students do want to learn, but that urban schools need more instructors who care. Dadier returns to school, and when the police question him, he refuses to identify his attackers. In class, Artie calls fellow student Pete Morales a "spic," whereupon Dadier remarks that calling one another names, like "spic, mick, and nigger," can lead to big trouble. Later the principal, acting on a confidential student complaint, accuses Dadier of bigotry, but Dadier angrily defends himself. Warnecke finally apologizes and puts Dadier in charge of the Christmas play. Soon afterward, West destroys Josh's prized record collection while his class looks on, leading the discouraged math teacher to resign. Meanwhile, Anne begins receiving anonymous letters and phone calls accusing her husband of infidelity. Unaware of Anne's growing suspicion, Dadier concentrates on his students. He convinces Miller and his singing group to perform their version of "Go Down, Moses" in the Christmas play, and he stimulates an animated class discussion by showing a "Jack and the Beanstalk" cartoon in class. Summarizing the discussion, Dadier encourages the young men to consider the real meaning of what they hear and to think for themselves. Miller later tells Dadier that because black people have limited options, he will drop out of school at term's end, but Dadier maintains that blacks can succeed in the modern world and that some teachers do care. At Christmas, Anne, tormented by the letters, gives birth prematurely, and when Dadier learns what has happened, he assumes the students are rsponsible for the letters and decides to resign. Defeated, Dadier bemoans that, after everything teachers must endure, they earn less even than cooks. Murdock, cured of his cynicism by Dadier's dedication, and Anne, admitting that she should not have doubted her husband, encourage Dadier to remain, and he does take heart when the doctor says his baby son is out of danger. Back at school, Dadier orders West to see the principal when the gang leader flagrantly cheats in class. West threatens him with a knife, ordering the other gang members to jump the teacher. To West's surprise, only Belazi obeys his orders. Following a scuffle, Dadier accuses West of having sent the anonymous letters and then drags him and Belazi to Warnecke's office. Later that day, Miller, having heard that Dadier plans to quit, promises to remain in school if Dadier will do the same.