In May 1953, a new group of Army recruits at Fort Bliss in El Paso, Texas encounter their drill instructors, Sgt. Laverne Holt and the tough young Sgt. Thorne Ryan. After Ryan's caustic appraisal of the recruits, Holt vows to make soldiers out of them during the sixteen weeks of basic training. Ryan, a combat veteran who resents his stateside duty, repeatedly applies for a transfer back to the Korean front. One night, the men cross the border to Mexico for recreation. In a bar, Ryan and Holt see a beautiful woman, Julie Mollison, buying drinks for a group of soldiers. Later that evening, the two sergeants escort the inebriated Julie to her apartment, and Ryan finds himself drawn to her. Training resumes, and Ryan exposes his men to tear gas to prepare them for the harsh conditions of battle. Ryan and Holt return to the bar one night, and find Julie sitting alone. When the crude Sgt. Vince Opperman insults Julie, she runs out of the bar in tears, and Holt comforts her. Ryan and Opperman fight, and Opperman reveals that Julie was married to a soldier who was killed in Korea shortly after she left him. One day, recruit Lobo Naglaski visits the camp chaplain to confess his murderous feelings toward Ryan, but comes to see that the sergeant has very little time in which to do a tough job. Tensions arise between Ryan and Holt, both over Ryan's callous treatment of the men and Holt's relationship with Julie. Ryan puts his men through increasingly tough drills, and during a bitter confrontation one day, Holt slugs Ryan and walks away. Later, Ryan calls on Julie at her apartment, and they fall into a passionate embrace. When she resists his further advances, however, Ryan becomes insulting, casting aspersions on Julie's virtue and chiding her for having left her late husband. One day, during a field exercise, recruit Donald Quentin Dover IV runs away. Ryan tracks him down and gives the young man a second chance, confessing that his own father had been a deserter. As the training period draws to a close, Ryan returns to Julie's apartment and discovers she has moved out. He finds Julie and Holt at the train station. After Holt leaves, Ryan apologizes for his earlier behavior and asks Julie to marry him, but she sadly replies that he is married to the Army. Outside the train station, Ryan and Holt silently make their peace. The men finish basic training, and as the new soldiers march by during their graduation exercises, Ryan proudly points them out to a fresh group of recruits.