In the short story The Fourth Man, Canon Parfitt is a senior clergyman from the diocese of Bradchester. He prides himself particularly on his "scientific sermons", which have been noticed and picked up by the press. He feels that the church really needed "good modern up-to-date stuff".
In the course of the story, Canon Parfitt finds himself sharing a train compartment with some acquaintances of contrasting occupations, Sir George Durand, an eminent lawyer, and Dr Campbell Clark, a noted psychiatrist. Their discussion of the mysterious life and death of one Felicie Bault forms the main plot of the story.