John is a young scientist working for CSIRO (the Commonwealth Scientific and Industrial Research Organization). More than any other character, he faces the reality of the situation and uses the last few months to realize and fulfill his dreams. Indeed, John truly lives for the first time only when he is in the shadow of death. Despite his fears, he goes on the submarine, and he takes even bigger risks when he races his Ferrari. Near the end of the novel, however, Osborne reaches his goal of winning the Australian Grand Prix. He also becomes a member of the Pastoral Club, an exclusive club he has always wanted to join. At the end of the novel, it is almost a shock to find out that John has a mother who is still alive. Although he is related to Moira and Douglas, John seems to be very much alone and not deeply connected to other people—in some sense, a misfit trying to be cool. John's death is lonely, but the way he wants it to be, in his Ferrari.

John's reaction to the war symbolizes the way the scientific community responds to the disaster. While scientists should be horrified about the war they have helped to create, they continue to objectively conduct experiments. John declares he will have fun discovering the effects of radiation poisoning, not considering the moral and ethical implications of having fun at the expense of millions of lives. It is this scientific objectivity and detachment that has made it possible for researchers to create the bombs in the first place. In his position as scientist and engineer, John is very much Shute's alter ego. From his own life experience as an engineer, Shute understands the minds of scientists and engineers who create weapons of war.