A red herring is a clue or “fact” that is used to distract attention from the real issue. In literature, a red herring is often a false clue. An author uses a red herring to mislead or distract the reader to deduce the wrong conclusion. Red herrings are particularly popular in suspense novels or thrillers, as the author uses them as false clues to lead the reader down the wrong path about who committed the crime. The Merriam-Webster dictionary says that the term stems from the use of a red herring, which emits a distinct scent to confuse hunting dogs.
A red herring that might be considered a traditional one is where the killer deliberately breaks a clock at the scene of the murder and resets the hands to point to a time for which he has an unassailable alibi. The nontraditional red herrings in Agatha Christie’s Murder on the Orient Express include various characters supplying alibis for others, swearing that they were together at the time of the murder. This turns out to be true because all the suspects colluded in the crime. Another nontraditional red herring is the use of foreign languages to throw the reader and the detectives off. One example is when the murder victim, Ratchett, is heard to yell from his drawing room on the night of the murder,
Ce n'est rien, c'est un cauchemar.
However, earlier, Ratchett had told Poirot that he did not speak French.
Another red herring that is somewhat nontraditional also involves the use of a foreign language. Specifically, the Countess’s handkerchief is embroidered with the letter “H.” However, the Countess’s husband swears that they were together at the time of the murder (which is, in itself, another red herring because they were together killing Ratchett). It turns out that the embroidered "H" is actually a Cyrillic Russian character that communicates a sound very close to the "N" sound in English.