Five Orange Seeds

Five Orange Seeds is the fifth of 12 stories in The Adventures of Sherlock Holmes.
In March 1883, Colonel Elias Openshaw received a letter from Pondicherry, India, containing only 5 orange seeds and the letters "K. K. K."
The colonel's behavior became strange: he either locked himself in his room and drank, or shouted. On May 2, 1883, he was found dead in the garden.
The colonel's nephew, young John Openshaw, turns to Sherlock Holmes. . .