‘Whodunnit’ stories (crime fiction where you have to guess who did it) often use a technique called a red herring to make the story more interesting. Literally ‘red herrings’ are red fish with a strong smell and were once used to train hunting dogs to follow a trail. In fiction, the term indicates a false clue which distracts the reader and stops him from understanding who the real criminal is. Often the red herring is a suspicious character who is really innocent but who confuses the reader until the end of the story.
Sir Arthur Conan Doyle uses the red herring technique to make his Sherlock Holmes stories more interesting. A classic example can be found in his story The Hound of the Baskervilles. While Holmes investigates the death of Charles Baskerville a mysterious character, an escaped prisoner, is seen near the scene of the crime. Everybody, including the reader, suspects that he is the murderer. It is only at the end of the story that they discover that he is not involved in the deaths at all. There are other red herrings, like the legendary curse of the Baskerville family. The reader wrongly believes in the curse and that it is the real motive for the murder.