Last Updated September 5, 2023.
There are two types of themes in the novel: first, political themes; second, personal themes.
An important political theme in Graham's novel is the hypocrisy and amorality of governments and their intelligence agencies. The British and Americans, for example, cynically and secretly work with the apartheid government in South Africa during the Cold War era to thwart communism while at the same time publicly condemning apartheid as an immoral system. As Graham writes in an introduction to the novel:
They [the West] simply could not let South Africa succumb to black power and Communism.
But the cynicism goes beyond fear of communism: Western business interests and governments are willing to turn a blind eye to the oppressions and human rights violations they publicly censure because there is money to be made.
A second and related theme of the novel is that espionage is far less about physical violence and thrilling acts of daring than it is about a willingness to behave in morally questionable ways to advance the amoral interests of a government. Green shows that loyalty to an intelligence agency is morally compromising and that there are often no "good" answers to moral dilemmas espionage poses.
A third, and more personal, theme is that we are haunted in middle age by a past we can never be free of. Castle does not feel "free" while alive: he sees death as freedom and longs for a fantasized land called Peace of Mind, but in the end can't shake the pain, even decades later, that he couldn't save his first wife from being killed in the bombing of London during World War II. He feels despair that intertwines with the mundane details of everyday life, suggesting it is ever present:
He took the glasses to the kitchen and washed them carefully. It was as though he were removing the fingerprints of his despair.
Finally, Greene reminds us in the novel that nobody is guaranteed a happy ending. Castle gets to Moscow and safety, but because of Sam not being on her passport, Sarah cannot join them. Somehow, Greene suggests, we have to come to spiritual terms with the way life really is—messy and sordid and compromised—rather than clinging to the dream of how we would like it to be.