Despite the health warnings, Dmitri continues with his experiments in fusion power. After a number of failures, he turns to Ilya for help. Whilst carrying out of the experiment successfully, Dmitri receives a new radiation dose. He tries to hide this fact from everyone, including his wife Lyolya who is misinterpreting his sudden isolation, though the truth eventually rises to the surface. The research work has been continued by Ilya. Dmitri's health is getting worse, but he decides to fight his illness to the end and agrees to undergo bone marrow transplantation.