PRESENTATION OUTLINE
Begins at 221B Baker Street, where Sherlock Holmes and Dr. Watson are sharing an apartment. Holmes is taking cocaine as an antidote to boredom, and Dr. Watson is concerned. There is a knock on the door, and Miss Mary Morstan enters.
Ten years earlier, in 1878, Miss Morstan's father had disappeared when on leave from military service in India. Starting in 1882, just after the death of her fathers only friend, Major Sholto, one valuable pearl had been sent to Mary each year. That morning she received a mysterious letter asking her to go the Lyceum Theater that evening. Holmes and Watson agree to go with her.
As they travel to the Lyceum, Mary continues her story. After her father's death, Mary discovered a paper with the diagram of a building and the words The Sign of the Four Jonathan Small, Mahomet Singh, Abdullah Kahn, Dost Akbar.
After meeting a man at the Lyceum Theater, Holmes, Watson and Miss Morstan are taken to meet Mr. Thaddeus Sholto, brother of Bartholomew and son of Major Sholto. On his deathbed, Major Sholto revealed that he and Morstan came into the possession of the Agra Treasure while stationed in India. Major Sholto told his sons to send one pearl each year to Mary Morstan. After being frightened by a face at the window, Major Sholto died before he could tell his sons where the treasure was hidden In the morning, a scrap of paper was found with the words The Sign of the Four written on it.
Bartholomew Sholto had recently found the treasure box, which contained a fortune in jewels. Holmes, Watson, Miss Morstan, and Thaddeus proceed to Pondicherry Lodge, Bartholomew's home. They find Bartholomew dead in his room, killed by a poisoned thorn. There is a torn sheet of paper on the desk with the words The Sign of the Four written upon it.
Following the clues, Holmes believes there are two participants in the crime, one has a wooden stump, the other has a small foot with distinctly divided toes. At that point Detective Athelny Jones arrives and arrests Thaddeus; he later arrests the gatekeeper, the housekeeper and the Indian servant at Pondicherry lodge.
Meanwhile, with the help of a dog named Toby, Holmes and Watson are led to the edge of a wharf. Holmes learns that a steam launch, the Aurora, was hired by a wooden-legged man and a brown, monkey-faced chap. Holmes asks Detective Jones to arrange for a police boat to meet Holmes, Watson and Jones at the river.
After a high speed chase, the police boat approaches the Aurora. Holmes and Watson are forced to shoot the small, dark man when they see him about to send a dart their way. They capture the man with the wooden leg, Jonathan Small, and find an iron chest on the deck of the boat.
Jonathan Small confirms that it was his accomplice, Tonga, who killed Mr. Sholto. When the iron chest is opened, it is discovered that Small had emptied the contents of the treasure box into the river.
In the final chapter of the book, Jonathan Small tells his story. During the Indian uprising, Small joined a plot to acquire a great treasure. While carrying out the plot, one man was killed and buried in a shallow grave. Small and his three Indian conspirators Mahomet Singh, Abdullah Kahn, and Dost Akbar were arrested for the murder. The treasure remained hidden.
The prisoners ended up in the Andaman Islands where Major Sholto and Captain Morstan were in command of the native troops. After Sholto and Morstan lost heavily playing cards, Small offered them a map to the treasure in exchange for helping him escape. Sholto took the map, retrieved the treasure, and returned to England.
The islander Tonga helped Small escape and go to England. After Captain Sholto died, Small looked for the jewels. When he couldn't locate them, he left the Sign of the Four pinned on Captain Sholto.
Years later, when Small learned the jewels had been found, he and Tonga went to Sholto's home. Small had no intention of killing Bartholomew and Tonga acted on his own.
As Small's story ended, Detective Jones took Jonathan Small into custody.
Dr. Watson informed Holmes that Miss Morstan accepted Watson's proposal of marriage.
The story concludes with Holmes turning once again to the cocaine bottle.
