The Sign of Four
   From the reminiscences of John H. Watson, M.D.
     by Sir Arthur Conan Doyle

"Following his successful resolution of the case of A Study in Scarlet, London's most ingenious detective is consulted by Mary Morstan, a young woman whose father had vanished years before. Since his disappearance, an unknown benefactor has been sending her a valuable pearl each year. Having received a note from the mysterious personage asking to meet her that evening, she invites Holmes and Watson to accompany her to the rendezvous. It soon becomes apparent that the disappearance of Ms. Morstan's father is somehow related to his military service in the Andaman Islands, a penal colony located between India and Burma."

“How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?”