The novel tells the story of a small group of cancer patients in Uzbekistan in 1955, in the post-Stalinist Soviet Union. It explores the moral responsibility — symbolized by the patients' malignant tumors — of those implicated in the suffering of their fellow citizens during Stalin's Great Purge, when millions were killed, sent to labor camps, or exiled.

One of the patients fears that a rehabilitated man he denounced eighteen years ago in order to obtain the whole apartment that they were living in together, will seek revenge, while others come to realize that their passive involvement, their failure to resist, renders them as guilty as any other. "You haven't had to do much lying, do you understand?" Shulubin tells the main character, Oleg Kostoglotov, who was in a labor camp. "At least you haven't had to stoop so low — you should appreciate that! You people were arrested, but we were herded into meetings to 'expose' you. They executed people like you, but they made us stand up and applaud the verdicts ... And not just applaud, they made us demand the firing squad, demand it!"