Tom and Cora Elliott love their active social life so much that they neglect their seventeen-year-old daughter Mary and fourteen-year-old son Les. Fred Mason, Tom's neighbor and the doctor at the defense plant employing Tom, worries about the effect that Tom and Cora's drinking and socializing have on the children. Les allows himself to be influenced by an older boy, Mike Taylor, who asks him to sneak Tom's gun out of the house. On the night that Mary goes to a party at Mason's house and becomes enamoured of his eighteeen-year-old son Joe, Les is injured when Mike accidentally fires the gun at him. Les's slight wound is tended to by Mason, who succumbs to Mary's pleas that he not report the incident to the police, even though physicians are required to report all gunshot wounds. The next day, Danny, one of the boys who witnessed the shooting, describes the incident to Sergeant O'Donnell of the juvenile bureau. As Mason and Tom are driving home that afternoon, Mason tells Tom about Les's injury and cautions him to supervise his children. Tom rudely tells Mason to mind his own business, and when he is met at home by O'Donnell, Tom incorrectly assumes that Mason involved the police. After Tom orders the lovestruck Mary to stop seeing Joe, the youngsters take other dates to the school dance, although they spend most of the evening with each other. Jealousies arise, however, and Mary leaves with Mike, whose erratic driving prompts Joe to follow him. Joe arrives on the scene just after the drunken Mike has struck a pedestrian, and after admonishing Mike to report the accident, Joe takes the injured man to the hospital. Mike does not go to the police though, and in order to protect Mary from any unpleasant implications, Joe takes responsibility for the accident and is expelled from school. Joe enlists in the Army, after which he asks Mary to elope with him. The couple drive across the state border and are married, but are spotted by Mike at an auto court. Mike phones Tom, who, unaware that Joe and Mary are wed, shoots and seriously wounds Joe. Desperate to protect her father, Mary convinces Joe to keep their marriage a secret until after Tom's trial for attempted murder. Using the defense of the "unwritten law" that a father must defend his daughter's virtue, Tom is acquitted. Afterward, however, when Mary reveals that she and Joe were married, police officer Nora Brooks tells her that she must face the consequences of her perjurious testimony. Mary readily acquiesces, although Nora allows her to leave for a week's honeymoon with Joe. Joe then reports to the Army, and Mary returns to live with the Masons and accept her responsibilities.