After her senses are surgically restored, a formerly deaf mute teenager enlists in the army and is assigned to communications work. But her inexperience with even such simple tasks as answering a telephone lead her supervisor to conclude she is incompetent, and try to have her reassigned. However, a courageous action by another soldier leads him to reevaluate his judgment.

生长在翡翠岭的农民女儿亚妹，已经聋哑了13年，解放军医疗队来到山村，向晖医生给亚妹精心治疗，使她恢复了听觉，开口说了话。亚妹感激党和毛主席给了她新生命，希望为革命贡献青春。在向晖的帮助下，亚妹穿上了军装。亚妹的好朋友阿燕，不安心本职工作，想去学医，亚妹批评了她，两人产生了隔阂。在指导员凌雪的帮助下，两人重归于好。在成绩考核中，亚妹接错了一次电话，蔡方成欲调她去做别的工作，司令员得知此事，说服了蔡方成，让亚妹留在通讯班。向晖是个老红军，战斗中负过伤，又因长期忘我地工作，积劳成疾。她的革命精神鼓舞着周围所有的人。向晖带病前来参加新式武器装备试验，使亚妹深受感动。她满怀激情填写了入党志愿书。向晖病情恶化，党中央派直升飞机接她到北京治疗，人们含泪把她送走。激烈的战斗中，亚妹坚守岗位，用耳朵和声音传达司令部的战斗号令，也将胜利的喜讯送到了北京。战斗结束了，亚妹从耳机中听到了向晖的声音：“为了壮丽的共产主义事业，让我们每个人都贡献出自己的青春！”