The Sign of the Four Themes

The Sign of the Four Themes

The Emptiness of Wealth

One of the strongest themes of Sign of the Four is the shallowness of wealth, and the destruction that can come through it. This theme arises again and again in Sign of the Four, as the Agra treasure directly and adversely affects almost everyone. In the course of the story, the Sheik’s emissary and Bartholomew are both murdered for the treasure, Tonga is killed while fleeing with it, and Small is sentenced to life imprisonment. Additionally, both Thaddeus and his father spent their lives in constant paranoia of wooden legged men, and strangers in general. The Agra treasure even provides a “romantic conflict” for Dr. Watson, who feels that he cannot marry Miss Morstan for fear that he will appear to be after her money.

"Invisible Evil"

Doyle, as well as many other mystery writers, makes use of a writing technique that can be thought of as “invisible evil.” Simply put, it is the phenomenon of criminal acts committed by unknown/unseen agents. Doyle plays on the “fear of the unknown” heavily in the course of the story; indeed the “sign of the four” itself carries with it mysterious and odious connotations. Also, the bizarre evidence found at the scene of the crime, namely the fact that Bartholomew was murdered in a locked room, serves to heighten the tension surrounding the idea of the “invisible assassins.”


The theme of “returning”, either literally or figuratively, is prevalent in Sign of the Four. The purpose of this theme is to heighten the importance surrounding the Agra treasure. Throughout the story, the appearance of the treasure leads to a direct, and often tragic change in the lives of the characters. Because of this, it is important that the removal of the treasure would cause the characters to return to their previous position. In the case of Small, a convict, the re-emergence of the treasure leads him down a path that ends in murder, and with the removal of the treasure, he is a prisoner once again. Mary Morstan is a charming young woman who Watson contemplates marrying. With the prospect of Mary becoming an heiress however, this possibility is removed. When it is discovered that the Agra treasure is gone, Mary returns to a position in which Watson can comfortably propose marriage. Perhaps the most poignant “return” is that of Holmes himself. At the beginning of the story, he can be found taking cocaine. This vice fades away while the problem of the Agra treasure is prevalent, but as soon as it is solved, Holmes digresses once again.

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