Book Summary

It begins when John Openshaw arrives from Horsham to the home of Sherlock Holmes telling Uncle John had two sons, Elijah and Joseph, the latter is the father of John.
His uncle emigrated to America where he worked as a settler and soldier then, where he lived for many years. Then he Horsham where one day suddenly received a letter from India, when open fall five orange pips and a note reading "KKK" John thought it was a letter omen and step enclosed days and as usual went out to walking the garden where hours later I found him drowned in a pose of only two feet deep, so the police decided it as a suicide.
 Four years later, for christmas, John hears a scream of his father and when he runs to see what happens, she realizes that her hand was a letter with five orange pips and a note reading "KKK" this it did not take much attention and three days later he was found dead in a sediment, police concluded it was an accident.
John tells what happened grabbing two years eight months and one day before it was to the home of Holmes had received the same letter that his uncle and his father.
Holmes looking in an encyclopedia which means the KKK initial and realizes that this is a clan that sends letters to people telling you that you will die, according to the encyclopedia this term movement suddenly.
John also took with him a calendar where his uncle out all the activities of this clan, when he saw Sherlock told him to put it in your yard to pick him up the clan and Juan obeyed and went home.
Sherlock Holmes the next day reading the newspaper realizes that John dead and begins to investigate where they come from three cards and searches that boat come here, is that the ship arrived at the port in a few days but it turns out it sank in a storm and only parts were found.