The Sign of Four (1890) is the second Sherlock Holmes novel by Arthur Conan Doyle. It is studied at GCSE as a 19th-century prose text and rewards analysis of Victorian society, the British Empire, class, and gender. The novel introduces Mary Morstan, who brings a mysterious case to Baker Street and becomes John Watson's wife.
What is the plot of The Sign of Four?
Mary Morstan comes to Baker Street with a puzzling history: her father disappeared ten years ago, and she has since received annual gifts of a rare pearl from an anonymous sender. She has now been invited to a meeting by a stranger. Holmes and Watson accompany her.
The case leads them to Bartholomew Sholto, whose father Major Sholto was an associate of Mary's father, Captain Morstan. The Sholto twins know where a vast treasure — the Agra treasure, stolen from India — is hidden. When Bartholomew is found murdered and the treasure stolen, Holmes is on the case.
The investigation leads to Jonathan Small, a one-legged ex-soldier who was involved in stealing the treasure during the Indian Mutiny (1857) alongside three Indian confederates (the 'Four' of the title). Small had been imprisoned on the Andaman Islands, where he befriended Tonga, an islander whose blowpipe kills Bartholomew. The climax is a Thames chase scene. Tonga is shot dead; Small is captured; and the treasure, thrown into the Thames by Small, is lost forever.
The novel ends with Watson proposing to Mary Morstan — but the loss of the treasure, which would have been her inheritance, is what frees him to propose (he could not, as a poor army surgeon, have proposed to a wealthy woman).
What are the key themes of The Sign of Four?
Empire, colonialism, and race. The novel is saturated with the British Empire. The treasure is plunder from India; Small is a casualty of the colonial system; Tonga is depicted in deeply troubling, racialised terms as a 'savage' with 'venomous' qualities. For a GCSE essay, it is important to analyse these representations as products of their historical moment — Conan Doyle reflects, rather than questions, the racial attitudes of Victorian imperialism. A strong essay can discuss how the novel othersises non-British characters and what this reveals about 19th-century ideology.
Justice and crime. Small is a complex figure: he was wronged by Major Sholto (who took his share of the treasure) and pursues revenge that has some logic to it. Yet his revenge involves murder. Conan Doyle creates a villain with a comprehensible grievance, which complicates the novel's moral landscape.
Reason and science. Holmes represents Enlightenment rationalism: he observes, deduces, and reaches conclusions through method rather than intuition. His famous opening deductions about Watson and Mary Morstan (reading their histories from physical details) dramatise the Victorian faith in observation as a path to truth.
Gender. Mary Morstan is the only significant female character, and she is consistently defined by her relationship to men: her missing father, the anonymous sender of pearls, and finally Watson. She is presented as brave and composed — Holmes calls her 'a very interesting woman' — but her role in the plot is that of a mystery object to be decoded rather than an agent.
Friendship and loyalty. Watson's narration is also a sustained celebration of his friendship with Holmes. The novel explores what binds Watson to Holmes despite (or because of) Holmes's eccentricities and emotional coldness.
Who are the key characters?
| Character | Role | Key feature |
|---|---|---|
| Sherlock Holmes | Consulting detective | Brilliant, cold, emotionally detached; uses cocaine ('a seven-per-cent solution') to manage boredom |
| John Watson | Narrator and companion | Warm, loyal, conventional; provides the emotional intelligence Holmes lacks |
| Mary Morstan | Client; Watson's future wife | Composed and perceptive; defined largely through Watson's admiring gaze |
| Jonathan Small | Antagonist | Complex villain; wronged man seeking justice; Conan Doyle gives him a full backstory |
| Tonga | Small's companion | Depicted in racialised Victorian terms as a 'savage'; his portrayal reflects imperial ideology |
| Athelney Jones | Police inspector | Contrasts with Holmes — conventional, blundering, quick to take credit |
What is the Victorian and historical context?
The Indian Mutiny (1857): Also known as the Indian Rebellion, this was a major uprising against British East India Company rule in India. Many British soldiers and administrators were involved, and the events left a deep psychological mark on Victorian Britain. Small's backstory is set during this period, and the treasure is linked to the chaos and violence of the colonial system at its most exposed.
Cocaine and Victorian medicine: Holmes's use of cocaine ('a seven-per-cent solution', which he injects) is not a sign of moral failure in the novel but reflects the Victorian medical understanding of cocaine as a stimulant and remedy. It signals the limits of contemporary scientific knowledge, even in the era of rationalism.
Class and social mobility: Watson's position as an army surgeon — respectable but not wealthy — is an important social context for his inability to propose to Mary while she might be an heiress. The Victorian class system is embedded in the plot's resolution.
Key quotations to learn
| Quotation | Speaker | Significance |
|---|---|---|
| 'When you have eliminated the impossible, whatever remains, however improbable, must be the truth.' | Holmes | Encapsulates Holmes's deductive method |
| 'I cannot live without brain-work. What else is there to live for?' | Holmes | Reveals his emotional coldness and intellectual obsession |
| 'Love is an emotional thing, and whatever is emotional is opposed to that true cold reason which I place above all things.' | Holmes | Key to his character; also frames Watson as his emotional opposite |
| 'You have been in Afghanistan, I perceive.' | Holmes | Holmes's deduction; demonstrates his method of reading physical evidence |
| 'She was weak, and gentle, and brave.' | Watson, of Mary | Reveals Victorian gender expectations in praise of Mary |
How do you write a GCSE essay on The Sign of Four?
- Choose a theme and sustain it. Empire and race, justice, or the Holmes–Watson dynamic all work well. Avoid trying to cover everything.
- Engage with historical context. GCSE mark schemes reward contextual knowledge that is woven into the analysis (not listed separately at the end).
- Analyse Conan Doyle's choices, not just the plot. Ask why Conan Doyle makes Holmes use cocaine, why Watson narrates, why Tonga is depicted as he is — the decisions behind the text, not just the content.
- Use the structure of the novel. The Thames chase is a climactic set piece; Small's backstory (told retrospectively) is a frame narrative within the main narrative. Both are worth discussing structurally.
Frequently asked questions
Why is Jonathan Small a complex character?
Small is unusual among Victorian villains because Conan Doyle gives him a backstory that creates genuine sympathy. Small made a terrible choice (joining the murder of a merchant for treasure during the chaos of the Mutiny), but he was imprisoned for years while his confederate Sholto profited from his share. His revenge is a form of justice — twisted and murderous, but intelligible. This moral complexity is what makes The Sign of Four more than a simple detective story.
How should I write about race and empire in The Sign of Four?
Write with historical awareness: Conan Doyle was not a uniquely racist writer but one who reproduced the racial assumptions of his time and class. Analyse how Tonga is described — the language used, the imagery, the contrast with the British characters — and consider what those representations reveal about Victorian imperial ideology. A strong essay does not simply condemn the text but uses it as historical evidence of how the British Empire shaped and distorted perception.
Why does Watson narrate instead of Holmes?
Watson's narration is a crucial structural and thematic choice. Holmes, narrating his own adventures, would be emotionally unintelligible — his coldness and his self-absorption would alienate the reader. Watson provides emotional warmth, admiration, and identification. He is the reader's point of entry into a world where Holmes's inhuman rationality would otherwise be unwelcoming. Watson's love for Mary Morstan also gives the novel its emotional sub-plot, which Holmes — who rejects emotion as inimical to reason — could never provide.
Is The Sign of Four the right Doyle text for AQA GCSE?
Yes — The Sign of Four is listed as a 19th-century novel option on the AQA GCSE English Literature specification. Check your school's scheme of work to confirm which text you are studying, as AQA offers several 19th-century prose choices. If you are unsure, your teacher is the authoritative source.
Working through The Sign of Four for GCSE? Professor Quill will help you develop your analysis and structure your essay argument. Visit aitutors.me.