The Sign of Four is the second of the four Sherlock Holmes novels, and offers a Victorian blend of horrid murder, treasure from the East, a woman wronged, an inheritance stolen and a midnight chase down the Thames in a steam-launch.
The novel begins with Holmes complaining of how boring and commonplace his life is, demanding of Watson “Was there ever such a dreary, dismal, unprofitable world?” Indeed the great detective has become so frustrated by London’s inability to provide him with any puzzles suitable for his intellect that he has taken to injecting a “a seven-per-cent solution” of cocaine to stimulate his mind. Watson, who deplores his use of drugs, attempts to distract him by providing him with an opportunity to deduce a man’s character and history from his pocket-watch, which Holmes unerring succeeds in doing. Soon they are interrupted by a Miss Morstan, who brings them a case which will involve a murder and a fabulous fortune in jewels, stolen during the Indian Mutiny.
Holmes is aided in his investigations by a superior sniffer-dog called Toby and the gang of street urchins whom he refers to as the “Baker Street Irregulars”. The regular police, in the form of Mr. Athelney Jones of Scotland Yard, do not come out of the case well. Though praised by the newspapers for his “well-known technical knowledge and his powers of minute observation”, Athelney Jones is a rather presumptuous and bumbling figure, prone to “attacks of energy” during which he arrests a number of people and comes no closer to the truth. Holmes is content to work behind the scenes, however, and allows Athelney Jones to take the final credit for the solution of the crime.
The Sign of Four isn’t all poisoned darts, criminal pacts and service revolvers, though. During the case Dr. Watson becomes increasingly enamoured of Miss Morstan, attracted by her “refined and sensitive nature” and her “singularly spiritual and sympathetic” blue eyes. However, Watson worries that revealing his affection would be seen as ignoble, since if they recover the Agra treasure Miss Morstan would be a fantastically wealthy heiress, and he is only “an Army surgeon with a weak leg and a weaker bank account.”
Despite all Holmes’ warnings that he should be careful of women as “the best of them are not to be trusted” and that emotion clouds the judgement of a rational mind, Watson’s undeclared love burns on within his bluff soldierly breast. When it turns out that the box believed to contain the treasure is empty, Watson feels that he can declare himself, proposes on the spot and the couple are engaged by the end of the novel.
On the final page, as Watson points out to Holmes, “The division seems rather unfair...You have done all the work in his business. I get a wife out of it, Jones gets the credit; pray what remains for you?” Holmes reaches for the cocaine bottle, and brings this most Victorian of crime novels to an end.