Since I haven't had the chance to read this novel, it's difficult to say precisely. However, based on the title, it may tell the story of Rosenberg's last days from different perspectives. It could show how he interacts with the people around him, like his family, friends, or enemies. The 'last days' part gives a sense of finality and urgency, so perhaps there are some secrets or revelations that come to light during this time. It might also be a character - study type of novel, focusing on Rosenberg's inner thoughts and emotions as he approaches the end of his life.