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The Great Agra Treasure was a collection of fine gems that were at the center of the events of The Sign of the Four. Originating in India, the treasure was sent to Agra for safekeeping during the Indian Rebellion of 1857. From there, it was stolen by Jonathan Small and a group of sepoys, setting into motion the events of the novel.


The treasure was initially collected by a wealthy rajah from a small state in the north of India. When the great uprising against the British broke out in 1857, the rajah decided to throw his support behind the sepoy rebels. However, fearing that the British would confiscate his wealth if the rebels lost, he divided it in half for protection. His gold and silver he kept in his palace; however, he collected his choicest gems and stones, and sent them to the Agra Fort in an iron box, where they could be hidden until the rebellion was over. Unfortunately, the treasure was stolen by Jonathan Small and three sepoys, who murdered the rajah's emissary. Unbeknownst to them, the rajah had secretly sent another servant to spy on the first, and this man alerted the guards, who quickly uncovered the emissary's corpse. The four men were put on trial for the murder; however, as the rajah had been deposed and fled from India as a result of the British victory, the existence of his treasure remained a secret. The four men were sentenced to a lifetime of penal servitude, and sent to the Andaman Islands.

During their imprisonment, Small met Major John Sholto and Captain Arthur Morstan. He attempted to bribe them to help him escape in exchange for a share of the treasure. Sholto agreed to help him escape, but asked to be allowed to verify the story first. Unsurprisingly, he betrayed the other me, stole the treasure for himself, and ran away to England, where he kept it hidden in his house, Pondicherry Lodge. Captain Morstan tracked him down to confront him about his actions, but died of apoplexy during the argument. Sholto covered up his death and disposed of the body. Although there was no one else in the country who knew of the treasure's existence, Sholto lived in fear that Jonathan Small would eventually appear to take his revenge.

Small eventually managed to escape from the island with the help of an Andaman native named Tonga. He made his way to England, where he tracked down Sholto, intent on recovering the treasure for himself. By this point, Sholto had become very ill, and had grown remorseful for the theft, and particularly for keeping the treasure from Morstan's orphaned daughter, Mary. He planned to tell his sons, Thaddeus and Bartholmew, where he had hidden the treasure. Unfortunately, Small's appearance at his window gave the ailing man a fatal shock before he could reveal its location. Small was forced to wait as the brothers conducted a fevered search for the treasure on their father's estate. In the meantime, they sent Mary a few loose pearls from the coronet anonymously, with the intent that she should get her full share when it was found.

At last, the Sholto brothers recovered the treasure, and notified Mary. She, understandably suspicious, hired Sherlock Holmes and John Watson to help her get to the bottom of this strange inheritance. In the meantime, Small also learned that the treasure was found, he and Tonga snuck into the house to steal it, with Tonga killing the unlucky Bartholomew in the process. The murder drew the attention of Scotland Yard. Holmes' investigation uncovered Small's involvement, and after a boat chase down the Thames, the convict was arrested. However, Small was unwilling to let anyone but himself benefit from the treasure. When the iron box was recovered, it was empty, and Small revealed that when it became clear he would be caught, he had emptied it into the river so its contents could never be recovered. Small claimed that that the treasure was a curse that brought bad luck to any man who owned it. The treasure was thus considered lost.

Surprisingly, Watson was greatly relieved by this development. He had grown very attracted to Mary over the course of the investigation, but considered it inappropriate to pursue her in light of her expected windfall. With the treasure lost, Watson moved forward with his proposal, which Mary gladly accepted. The two married soon afterwards.


The treasure consisted of 143 diamonds, including the "Great Mogul", said to be the second-largest in existence; 97 emeralds; 170 rubies; 40 carbuncles; 210 sapphires; 61 agates; and an unknown number of beryls, onyxes, cats'-eyes, turquoises, and other stones. It also included almost 300 pearls, twelve of which were set in a gold coronet. Almost the entire treasure is lost by the end of the story, with only the chest, Mary's six pearls and the gold coronet remaining.


  • The Great Mogul Diamond was a real stone, originally weighing 787 carats. It was gifted to the Mughal emperor Shah Jahan, who had it cut down to 280 carats. The stone was taken to Persia by Nadir Shah's after his defeat of the Mughals in 1739, but was lost after his assassination in 1747. Wikipedia link.