The Five Orange Pips - Sir Arthur Conan Doyle

John Openshaw lives with his uncle Elias, who used to live on a plantation in the States. Strange things have been happening of late in their home. There's a door that is always locked and his uncle's behaviour has become erratic. One day, a letter arrives from India with only the mention "K. K. K." on it. It contained five orange pips. "The Five Orange Pips" is part of "The Adventures of Sherlock Holmes".