Because it belongs to a vast and developing saga of Sherlock Holmes’s career, “A Case of Identity” can be approached both as an episodic slice of a much bigger narrative and as a stand-alone story. Conan Doyle even wrote the characters’ dialogue in such a way that invokes the overarching storyline as Holmes and Watson discuss their past cases together; this frames the tale within the broader, intertextual Holmes context.

As a stand-alone work, however, the story follows what is at first an obvious thematic outline: At the beginning, Holmes details a philosophy about life and human psychology that, as the plot unfolds, is brought further to light.

Holmes hypothesizes in the opening paragraphs that “it is usually in unimportant matters that there is a field for the observation, and for the quick analysis of cause and effect which gives the charm to an investigation” (226). Holmes has a complex rationality involving both an inductive and deductive approach. Deductive reasoning, which involves forming a hypothesis and then testing it through observation, appears in this quote—which is itself a kind of hypothesis. Conan Doyle gradually corroborates this claim; Holmes’s attention to detail and observance of the “unimportant matters” are precisely what solve the case.