The Sign of Four + The Hound of the Baskervilles

Arthur Conan Doyle · 1890, 1902

Premise

In two of Arthur Conan Doyle's novels, Sherlock Holmes, a consulting detective in London, solves a murder over a stolen Indian treasure and a death on Dartmoor blamed on a supernatural hound, both narrated by his friend Dr John Watson; together they show a method of thinking that trusts observation and reason over appearance, legend and fear, and the cost to the mind that lives only for problems.

This guide discusses the whole plot of both novels, including the endings.

The main ideas

Careful observation of small details reveals what others overlook.
When you have eliminated the impossible, whatever remains, however improbable, must be the truth.
A mind built for problems suffers without them.
Wealth gained by crime corrupts everyone who touches it.
Apparently supernatural events have natural explanations, often human ones.
People and places are rarely what they first appear.
A good narrator, slower than the hero, lets the reader follow the reasoning.

The science of deduction

The Sign of Four, published in 1890, opens with Holmes demonstrating his method on Watson. Watson hands him a watch and challenges him to deduce something about its owner. From scratches, pawnbrokers' marks and the state of the keyhole, Holmes deduces that it belonged to Watson's elder brother, a man of careless habits who had good prospects, fell into poverty and drank. Watson is hurt, thinking Holmes must have made inquiries. Holmes explains each inference.

Later in the novel, Holmes states the principle most associated with him: when you have eliminated the impossible, whatever remains, however improbable, must be the truth.

His method combines close observation, broad specialized knowledge and the willingness to follow evidence to unexpected conclusions.

The mechanism is that most people see without observing. Attending deliberately to details that seem trivial supplies evidence others never notice.

Implication: before drawing a conclusion, look for the small, specific details of a situation and ask what each one implies.

A mind that rebels at stagnation

The same novel opens with Holmes injecting himself with cocaine. When Watson protests, Holmes explains that his mind rebels at stagnation. Given a problem, he needs no artificial stimulant; without one, he cannot bear the dullness of existence.

The case that follows rescues him from boredom. At its end, Watson announces that he is engaged to Mary Morstan, the client, and observes that he has gained a wife and others the credit, and asks what remains for Holmes. Holmes answers that for him there still remains the cocaine bottle.

The mechanism is that a mind tuned for intense problem-solving finds ordinary life intolerable, and seeks stimulation wherever it can.

Implication: if your work is the main source of your stimulation, consider what fills the gaps between challenges, and whether it does you harm.

The Agra treasure

Mary Morstan comes to Baker Street with a mystery. Her father, an army officer, vanished ten years earlier. Some years later, after she answered a newspaper advertisement asking for her address, she began to receive a single pearl every year from an unknown sender. Now a letter asks her to a meeting.

The trail leads to the Sholto brothers, whose father served with hers in India and came home with a great treasure. When the treasure is found, one brother is murdered in a locked room by a poisoned thorn. Holmes, aided by a tracking dog and a band of street boys, traces the killers: Jonathan Small, a one-legged former soldier, and his companion Tonga, an islander from the Andamans. After a chase down the Thames, Tonga is shot and Small captured. The treasure box is empty. Small has thrown the jewels into the river.

Small tells the story behind it. During the Indian rebellion of 1857, he and three companions murdered a man posing as a merchant who was carrying a rajah's treasure, and took the jewels. The treasure brought betrayal and ruin to everyone who held it.

The mechanism is that wealth taken by crime binds its holders in suspicion and betrayal, so it destroys them rather than enriching them.

Implication: judge a fortune by how it was obtained. Gains won by wrongdoing carry obligations and dangers that can outweigh their value.

The legend of the hound

The Hound of the Baskervilles, serialized in 1901 and 1902, begins with an old family legend. A seventeenth-century ancestor, Hugo Baskerville, was killed on Dartmoor by a spectral hound, and the curse is said to haunt his descendants. Now Sir Charles Baskerville has been found dead on the moor, apparently of fright, and a little distance from his body Dr Mortimer saw the footprints of a gigantic hound.

Holmes refuses the supernatural explanation. He assumes that a human agent is at work and that the legend is being used, perhaps deliberately, to frighten.

He is right. The hound is real, a huge dog made to glow with phosphorus, and its master is the naturalist Jack Stapleton, a hidden heir to the Baskerville fortune, who means to kill the heirs standing between him and the estate.

The mechanism is that a frightening legend provides cover for a crime, because people who believe in the supernatural stop looking for human causes.

Implication: when an event seems to have a mysterious explanation, look first for someone who benefits from that belief.

Appearances on the moor

Holmes sends Watson to Dartmoor to protect the new heir, Sir Henry Baskerville, and report back. Watson finds a landscape of suspicious figures: the Baskervilles' butler Barrymore, signaling at night across the moor; an escaped convict hiding in the hills; and a stranger living in a stone hut.

Each mystery has an innocent or surprising explanation. Barrymore is helping his wife's brother, the convict. The stranger in the hut is Holmes himself, secretly investigating while Watson draws attention. And the friendly Stapleton, who introduces a woman as his sister, has in fact been passing off his wife as his sister to use her in his scheme.

The convict, wearing old clothes of Sir Henry's, is hunted by the hound in Sir Henry's place and falls to his death on the rocks. In the end, Holmes and Watson save Sir Henry from the hound, and Stapleton flees into the Grimpen Mire, a deadly bog, and is never seen again.

The mechanism is that people who seem suspicious often have ordinary secrets, while the dangerous one is often the person who seems most helpful.

Implication: separate what is merely odd from what is actually threatening, and do not let a pleasant manner exempt anyone from suspicion.

Watson

Both novels are narrated by Watson, a doctor and former army surgeon, who is intelligent and brave but slower than Holmes. He records what he sees without understanding it, so that the reader, like Watson, is given the clues but not the conclusions.

In The Hound of the Baskervilles, Doyle gives Watson his largest role, sending him alone to the moor while Holmes stays hidden. His reports, and his mistakes, carry much of the novel.

The mechanism is that a narrator who sees the evidence without grasping its meaning lets readers attempt the solution themselves, and makes Holmes's reasoning visible when it is revealed.

Implication: when explaining a line of reasoning, show the evidence before the conclusion, so that others can follow the steps.

Where it falls short

Its imperial outlook is ugly. The Sign of Four depicts Tonga as a savage and treats Indian and Andamanese characters through crude racial stereotypes common in Victorian Britain.
Its women are mostly passive. Mary Morstan exists largely to be rescued and married, and Beryl Stapleton is a pawn in her husband's scheme.
Its detective is infallible by design. Holmes's deductions often depend on coincidence and on inferences that only the author can guarantee are correct, so the method looks more reliable on the page than it would be in life.

Strange Case of Dr Jekyll and Mr Hyde — another Victorian London mystery in which a rational investigator uncovers a hidden truth.
Diary of a Drug Fiend — cocaine's appeal and its cost, from the other side.
Thinking, Fast and Slow — the research on why careful observation and slow reasoning are hard.