The Sign of the Four Study Guide

Characters

• Sherlock HolmesWith the case over, he rejects marriage as a threat to judgement and reaches for cocaine.First appears: Chapter 1: The Science of Deduction
• Dr WatsonHe tells Holmes that Mary has agreed to marry him and fears that this may end his participation in their investigations.First appears: Chapter 1: The Science of Deduction
• WBWatson's brotherWatson's late elder brother, whose carelessness, financial difficulties and drinking Holmes correctly infers from the marks on his watch.First appears: Chapter 1: The Science of Deduction
• HMrs HudsonAlarmed by Holmes's constant pacing and muttering, she tells Watson that she fears for his health.First appears: Chapter 1: The Science of Deduction
• Athelney JonesHe takes Small away after hearing his account and tells Holmes and Watson that they will be needed at the trial.First appears: Chapter 1: The Science of Deduction
• Miss Mary MorstanWatson announces that she has agreed to marry him.First appears: Chapter 1: The Science of Deduction
• Captain Arthur MorstanSmall says he joined Sholto's bargain to free the four convicts for a share of the treasure, but was cheated when Sholto took it all.First appears: Chapter 2: The Statement of the Case
• CFMrs Cecil ForresterShe waits up for Mary's return and welcomes her with the affection of a mother rather than treating her as a paid dependant.First appears: Chapter 2: The Statement of the Case
• Major John SholtoSmall says he promised to arrange the four convicts' escape in exchange for a share of their treasure, then took all the jewels and left them imprisoned.First appears: Chapter 2: The Statement of the Case
• WWilliamsThaddeus's trusted driver, a former boxing champion who once served as a porter protecting Major Sholto.First appears: Chapter 3: In Quest of a Solution
• ISThe Indian servantA servant wearing a yellow turban and sash who admits the visitors to the suburban house.First appears: Chapter 3: In Quest of a Solution
• Thaddeus SholtoHe is released after proving an alibi that rules out Jones's accusation against him.First appears: Chapter 3: In Quest of a Solution
• Jonathan SmallHe admits helping to murder Achmet, killing a prison guard and scattering the treasure in the Thames, while defending his claim to the jewels.First appears: Chapter 3: In Quest of a Solution
• MSMuhammad SinghSmall identifies him as one of the Sikh guards who forced him into the treasure plot and says he remained at the gate while the others concealed Achmet's body.First appears: Chapter 3: In Quest of a Solution
• AKAbdullah KhanAccording to Small, he threatened Small into joining the plot to kill Achmet and later shared the agreement with Sholto and Morstan.First appears: Chapter 3: In Quest of a Solution
• DADost AkbarAccording to Small, he is Abdullah's foster-brother who devised the robbery, led Achmet to the fort and stabbed him after Small tripped him.First appears: Chapter 3: In Quest of a Solution
• Bartholomew SholtoAccording to Small, Tonga killed him before Small entered the laboratory to take the treasure.First appears: Chapter 4: The Story of the Bald-Headed Man
• LCLal ChowdarMajor Sholto's now-dead servant, who, in the major's reported account, believed Sholto had killed Morstan and helped conceal the body.First appears: Chapter 4: The Story of the Bald-Headed Man
• McMurdoThe police have arrested him as an accessory to the crime at Pondicherry Lodge.First appears: Chapter 5: The Tragedy of Pondicherry Lodge
• Mrs BernstoneA newspaper reports that she has been released along with Thaddeus Sholto.First appears: Chapter 5: The Tragedy of Pondicherry Lodge
• TTongaSmall says he nursed Tonga back to health and escaped with his help, but that Tonga later killed Bartholomew against Small's wishes.First appears: Chapter 6: Sherlock Holmes Gives a Demonstration
• SShermanAn elderly animal keeper who lends Watson Toby once he learns that Holmes has sent him.First appears: Chapter 6: Sherlock Holmes Gives a Demonstration
• TTobyAfter being returned to the point where two scent trails crossed, he follows the other trail to a riverside wharf.First appears: Chapter 6: Sherlock Holmes Gives a Demonstration
• LRLal RaoHolmes identifies him as Small's inside accomplice at Pondicherry Lodge, although Small refuses to name his informant.First appears: Chapter 6: Sherlock Holmes Gives a Demonstration
• MSMordecai SmithHe denies knowing about the Norwood crime, and Small confirms that they hired him without telling him about it.First appears: Chapter 8: The Baker Street Irregulars
• SMrs SmithMordecai Smith's worried wife, who tells Holmes about the wooden-legged visitor and describes the missing Aurora.First appears: Chapter 8: The Baker Street Irregulars
• JJackThe Smiths' young son, whom Holmes gives two shillings before questioning his mother.First appears: Chapter 8: The Baker Street Irregulars
• JJimHe steers the Aurora during the chase and is taken aboard the police launch with his father.First appears: Chapter 8: The Baker Street Irregulars
• WigginsThe leader of Holmes's young street informants, who brings the Baker Street Irregulars to receive instructions for finding the Aurora.First appears: Chapter 8: The Baker Street Irregulars
• FAThe foreman at Jacobson's YardHe tells the disguised Holmes that the Aurora is in the yard for a rudder repair even though nothing is wrong with it.First appears: Chapter 10: The End of the Islander
• AchmetAccording to Small, he was carrying a rajah's jewels to safety under a merchant's disguise when Small and his companions murdered him at Agra.First appears: Chapter 11: The Great Agra Treasure
• RThe rajahAccording to Abdullah's story, reported by Small, he sent his jewels to Agra with Achmet while supporting the rebellion, hoping to preserve wealth whichever side won.First appears: Chapter 12: The Strange Story of Jonathan Small
• CThe convict-guardSmall says he killed this unnamed prison guard with his wooden leg during his escape from the Andamans.First appears: Chapter 12: The Strange Story of Jonathan Small

Chapter summaries

1. Chapter 1: The Science of Deduction

   Watson watches Holmes inject cocaine and finally protests as both his friend and a doctor. Holmes admits its physical dangers but says that difficult problems provide the mental stimulation he needs without drugs. Their disagreement extends to storytelling: Holmes wants detection treated as an exact science, while Watson defends the human interest in his written account of a previous case. Holmes distinguishes observation from deduction by explaining how he knew Watson had sent a telegram. When Watson tests him with a watch, Holmes correctly infers his late brother's carelessness, poverty and drinking from its marks. Watson's distress makes Holmes recognise the pain behind what he has treated as an abstract problem. A visiting card interrupts Holmes's complaint that he has no work worthy of his abilities.

2. Chapter 2: The Statement of the Case

   Mary Morstan seeks help over her father's disappearance and a series of unexplained gifts. Her father returned to London on leave from his regiment but vanished before she could meet him, and Major Sholto, his one known friend there, denied knowing of his arrival. Years later an anonymous advertisement led to a pearl arriving by post, followed by one each year until Mary had six. The latest letter promises justice at a secret meeting and allows her to bring two friends, so Holmes and Watson agree to go. Holmes links the letter's handwriting to the disguised addresses on the pearl boxes. Watson admires Mary's appearance and manner, whereas Holmes insists that personal attraction must not influence judgement. Alone, Watson tries to dismiss his romantic hopes because of his poor health and limited money.

3. Chapter 3: In Quest of a Solution

   Holmes uses a newspaper death notice to connect Major Sholto's death with the start of Mary's anonymous gifts. He suggests that Sholto's heir knows something about her father's disappearance, but Watson points out questions that this theory cannot answer. On the way to the meeting, Mary produces a paper found among her father's possessions, showing a building plan, a red cross, four names and a strange sign. Holmes cannot yet explain it and acknowledges that the case is more complicated than he thought. The fog and shifting lights make Watson anxious, while Holmes remains absorbed in his notes and follows their route accurately. A coachman at the Lyceum insists on excluding police officers before taking them to an unknown destination south of the river. Watson finds the Indian servant at the ordinary suburban doorway incongruous, bringing the story's Indian connections into the London setting.

4. Chapter 4: The Story of the Bald-Headed Man

   Thaddeus Sholto receives the visitors in a richly furnished room and asks them to keep police and officials out of the affair. He recounts his father Major Sholto's deathbed confession that Captain Morstan died during a quarrel over treasure and that the major concealed the body to avoid suspicion and disclosure. The major's attempt to excuse himself sits uneasily beside his admission that greed made him withhold Morstan's share from Mary. Before he could reveal the hiding place, a face at the window terrified him and he died; his room was later searched and a note bearing "The sign of the four" was left on his body. Thaddeus says he sent Mary the pearls after persuading Bartholomew, treating her claim as a duty rather than a gift. Bartholomew has now located the treasure in a concealed garret by measuring the house. As they travel to Pondicherry Lodge, Watson feels ashamed that Mary's possible fortune brings him misery rather than happiness.

5. Chapter 5: The Tragedy of Pondicherry Lodge

   McMurdo initially bars the visitors from Pondicherry Lodge but admits them after recognising Holmes from a boxing match. The house's silence and the housekeeper's frightened crying unsettle the party, while Watson and Mary find comfort in holding hands. Mary calms Mrs Bernstone and remains with her as Holmes, Watson and Thaddeus go upstairs to investigate Bartholomew's failure to answer his door. They force their way into a room bolted from inside and find Bartholomew dead in a laboratory, his face fixed in an unnatural grin. A stone-headed stick and a note saying "The sign of the four" lie nearby, and Holmes identifies a thorn above the ear as poisoned. Thaddeus says the treasure has vanished and fears being blamed because he helped lower it from the garret and left Bartholomew alone the night before. Holmes reassures him and advises him to inform the police, while maintaining that the evidence is making the case clearer.

6. Chapter 6: Sherlock Holmes Gives a Demonstration

   Holmes uses muddy marks and a bloodstained rope to reconstruct how a wooden-legged man reached the high window with an accomplice's help. A trapdoor in the garret explains the accomplice's entrance, while tiny bare footprints briefly unsettle both investigators. A mark in spilt creosote gives Holmes a scent trail, and the body's extreme rigidity supports his conclusion that the thorn carried poison. Athelney Jones mocks Holmes's theories but repeatedly adjusts his own explanation to make Thaddeus guilty, even when Holmes presents awkward evidence. Jones arrests Thaddeus, exposing the danger of official confidence unsupported by careful reasoning. Holmes promises to clear him, identifies Jonathan Small as the likely wooden-legged intruder, and asks Watson to escort Mary home before bringing back Toby.

7. Chapter 7: The Episode of the Barrel

   Watson restrains his love because Mary is distressed and because her possible fortune makes him fear appearing interested in her money. Mrs Forrester's affectionate welcome gives him a glimpse of domestic peace before he fetches Toby from Sherman's animal-filled house. Back at Pondicherry Lodge, he learns that Jones has extended his arrests, while Holmes compares the bare footprints and retraces the accomplice's route across the roof. A dropped pouch of wooden spines like the murder weapon strengthens Holmes's interpretation of the crime. As Toby follows the creosote, Holmes reconstructs Small's history as a convict seeking treasure and revenge, and argues that the accomplice killed Bartholomew against Small's wishes. Watson questions the speculative basis of the account before accepting Holmes's explanation of Small's identity. The confident pursuit ends comically at a barrel smelling of creosote, making the strength of a scent distinct from proof that it belongs to the fugitives.

8. Chapter 8: The Baker Street Irregulars

   Holmes explains the mistaken trail and leads Toby back to follow the other scent to the river, where the scent trail ends. By pretending to be a customer and offering false details for Mrs Smith to correct, he draws out an account of her husband's departure and a description of the Aurora. He rejects a public advertisement that might warn the fugitives and instead recruits the Baker Street Irregulars to search both banks. Watson remains committed to recovering Mary's share despite believing that wealth would place her beyond his reach, so affection becomes a motive for work rather than a distraction from it. The newspaper praises Jones and credits him with deductions Holmes made, exposing the gap between the reader's knowledge and the public account. Holmes links the unnamed accomplice to the Andaman Islands through his footprints and weapons, supported by a gazetteer whose hostile generalisations turn an entire people into a source of fear. The chapter ends with the search unresolved and Holmes playing the violin to soothe the exhausted Watson to sleep.

9. Chapter 9: A Break in the Chain

   While the search for the Aurora stalls, Holmes becomes sleepless and irritable, showing how much his composure depends on progress. Watson visits Mary, who cares more about clearing Thaddeus than gaining a fortune. Holmes eventually goes out in disguise, leaving Watson to receive messages. A newspaper reports Thaddeus and Mrs Bernstone's release, but the long wait makes Watson question whether Holmes has misread the evidence. Jones arrives and admits that Thaddeus's alibi has destroyed his own theory. Holmes returns as an elderly sailor and deceives both men before revealing himself. He takes command of a planned police expedition, obtaining permission to question Small and let Watson show Mary the chest if it is recovered.

10. Chapter 10: The End of the Islander

    Holmes explains that changing to chemical work let him reconsider the missing launch. By imagining how Small could keep the Aurora ready while hiding it, he reasoned that a repair yard offered a suitable cover. His search found the launch at Jacobson's Yard, with a pretended rudder repair and a collection arranged for that evening. A boy's signal alerts the waiting police launch, but the Aurora's speed and an obstructing tug make the chase uncertain. Watson's hostile animal imagery makes the islander seem less than human; Holmes and Watson then fire as the man lifts his weapon to his lips. The islander falls into the river, while the wooden-legged fugitive runs the Aurora aground and becomes trapped in the mud. The pursuers recover an iron chest, and a dart lodged behind Holmes and Watson shows how narrowly they escaped death.

11. Chapter 11: The Great Agra Treasure

    Small denies responsibility for Bartholomew's death, naming Tonga as the killer and saying he had expected the room to be empty. He distinguishes his lack of hostility towards Bartholomew from his willingness to kill Major Sholto, while presenting the treasure as a curse on everyone who has possessed it. Holmes offers to hear his account and thinks he can establish that Bartholomew was dead before Small reached the room. Jones reports Smith's denial of knowledge of the crime, which Small supports by explaining that the boatman was paid without being told their business. With an inspector waiting outside, Watson takes the chest to Mary and tries to sound delighted at her expected wealth. Opening it reveals that its weight comes from the ironwork and that no treasure remains inside. Freed from what he sees as the barrier of her wealth, Watson declares his love, and her reply makes the loss of money a moment of shared happiness.

12. Chapter 12: The Strange Story of Jonathan Small

    Small says he scattered the jewels along the Thames so that nobody else could enjoy the treasure he claims for himself and his three imprisoned companions. Looking back to his life in India, he describes joining three Sikhs in a plot to murder Achmet, a rajah's servant carrying the jewels. Watson is horrified by Small's part in Achmet's murder and still more by his casual manner of recounting it, casting doubt on Small's attempt to present himself as a victim. Convicted alongside his accomplices, Small later bargains with the indebted Sholto and Morstan for all four convicts' release, but Sholto takes the jewels and abandons them. Small says he nursed Tonga back to health, killed a guard during their escape and eventually reached England with Tonga to pursue Sholto. His account explains the signs left after both Sholtos' deaths and blames Tonga for killing Bartholomew before Small entered the room. After Jones takes Small away, Watson announces his engagement to Mary, while Holmes rejects marriage as a threat to reason and reaches for cocaine.

Key quotes