The sign of the four

"The Sign of Four, Arthur Conan Doyle's second novel about the exploits of Sherlock Holmes, first appeared in England and the U.S. in "Lippincott Magazinein February 1890. "The Sign of Fourbrings Mary Morstan, a beautiful young governess, to the home of consulting detective Sherlock Holmes and Dr. John Watson. Mary's father, an officer in the British Forces who had served as a prison guard in India, disappeared the day he returned to England six years earlier - while en route to meet his daughter.

One year to the day after Captain Morstan's disappearance, Miss Morstan received a small box containing a lustrous pearl.

No return address, no note, just the jewel. On each successive anniversary over the next several years another pearl arrived from her unknown benefactor.

Determined to uncover the story behind the elder Morstan's disappearance, and the meaning behind the mysterious jewels, the trio set out on an exotic adventure laced with stolen treasure, secret oaths and murder, culminating in a breath-taking chase down the Thames.