The titular Mr Dixon is not the novel's main character but the creation of the novel's main character, Tom Spence. Spence describes himself as "an embryo novelist"; he has had the odd job - for example, delivering mail - but is largely without skills and has bet all on his career as a writer. Unfortunately he has "never brought a novel to a successful conclusion" never mind had one published, and, unable to live the dream, has instead dreamed it through his protagonist, Drew Dixon. His novel has ground to a halt because he has decided Dixon will "meet a girl of twenty-five or thereabouts whose entry into his world was to change his life" but has no idea how to write it. Fortuitously he meets a young woman, Ann, and, as their relationship develops we begin to sense that it will be Spence's life that is changed rather than Dixon's.

As Spence's isolation ends he revisits his past, attempting to contact the mother he hasn't seen in years and returning to his old school to see the English teacher who he believes encouraged him to write. Increasingly his admiration for Dixon turns to hatred and Spence is forced to choose between life and art.