Last Updated September 5, 2023.
Wilkie Collins's The Moonstone is a seminal work in the field of detective literature. The story begins with Colonel Herncastle, the older and rather unkind uncle of Rachel Verinder, returning from India during Britain's rule of the nation. Colonel Herncastle comes home with a large and opulent diamond in tow—the Moonstone. The stone is a very precious gem to practitioners of Hinduism, and he knows that its rightful owners will want to get it back and that it will be widely recognized. In an act of anger, he leaves it in his will to his niece because he wants his family to be punished for having shunned him.
Rachel receives the Moonstone and wears it to dinner on her eighteenth birthday, a rich affair where she has many suitors. A number of maids and servants are present, including a group of Indian jugglers. The stone disappears from Rachel's room and cannot be found. Blame is cast alternately on Rachel, the jugglers, and one of the maids, Rosanna, who commits suicide by quicksand after behaving strangely throughout the dinner.
When Franklin Blake, one of Rachel's suitors, returns from abroad a year later, he realizes Rosanna was in love with him and had thought he was the thief; she tried to cover up the crime to save him before she committed suicide out of guilt and grief. The stone is presumed to be in a London bank vault, but Rachel reveals she had actually seen Franklin take the diamond, confirming him to be the thief. Not believing this or remembering having committed any sort of crime, Franklin eventually learns that he was drugged at the party and, in a trance, stole the stone to move it to a safe place. But how it got to a London vault, he doesn't know.
Franklin and his fellows attempt to track down the stone, learning that it was taken from the vault. They track it to a rundown inn, where they find the body of a man killed by the Indian jugglers and that the stone has been stolen. The real thief is revealed to be Godfrey Ablewhite, another suitor from the party who had embezzled a trust fund and was planning to use the diamond to replenish it. He had encountered Franklin after he had stolen the diamond and taken it from him, knowing the Moonstone would pay off his debts.
In the end, with the mystery resolved, Franklin and Rachel marry, and it is revealed that the stone has been returned to its native India, to the people to whom it rightfully belongs.