en Cuevana 3. Two young scientists are exploring new fields of nuclear physics. Dmitry Gusev and Ilya Kulikov are good friends, but rivals in love. Dmitry marries Lyolya and they live happily together. Luck has it that he makes an important discovery. Unfortunately he exposes himself to radioactivity during the experiments. As a result he falls seriously ill. However Dmitry has a strong spirit. His will to live, the deep passion for his work and his strong love for mankind makes it possible for him to recover.