在这部当我们年轻的时候剧情片中,：第二次世界大战期间，以大学生季莫和印刷女工薇丝卡为首的一群青年放弃了自己的学业和工作。积极投入反法西斯的地下斗争。他们动用自己的智慧和勇气，想出来的斗争方式多种多样。有的到剧场散发传单宣传革命精神；有的埋伏在酒馆炸死敌军官；有的烧毁敌人的军队，军火库；有的炸毁法西斯分子的碉堡，桥梁；有的出其不意的夺走敌人军火库的枪支弹药等等。由于缺乏经验和人手，以及更加强有力的组织，斗争有的成功了，有的失败了。季莫和薇丝卡也在一次意外中不幸被捕，献出了年轻宝贵的生命，为同志们树立了英勇的榜样。他们的反法西斯战斗小组织依然存在，他们开始总结经验投入更大规模中的战斗中，他们前仆后继，继续狠狠的打击了敌人，削弱了法西斯的反动势力。
Dimo and Veska, members of a combat group made by the young people, get acquainted at the secret meeting. The group's first operation fails: the bomb placed in the theatre does not go off. Owning to Dimo, the second assignment goes wrong. He is suspecting of being a traitor. The leader of the group, Mladen, narrowly escapes an ambush. After a discussion, the group decides to isolate Dimo. Veska, who is in love with him, has faith in him. The traitor is Slavcho, a former colleague of Veska and now police agent. He keeps calling on Veska and spies on the young people. He visits Dimo's neighbor Tzveta several times too. Confined to a wheelchair, Tzveta goes in for photography. From her negatives, the agent learns of Mladen's visits to Dimo. The questions he asks her make it clear to Tzveta that Slavcho works for police. She tries to warn Dimo, but on the way her wheelchair goes out of control, she crashes into tree and dies. Dimo is arrested. He withstands terrible torture at the police ...
