macguffin

A plot device that motivates the characters and advance the story, particularly one whose importance is accepted completely by the story's characters, yet from the audience's perspective it might be minimally explained or may test their suspension of disbelief if it is scrutinized. The device, usually an object, is common in films, especially thrillers. It is important that the audience never actually see the MacGuffin. I dunno why. The term "MacGuffin" was invented by Alfred Hitchcock; according to the Oxford English Dictionary, he explained the term in a 1939 lecture at Columbia University: In regard to the tune, we have a name in the studio, and we call it the 'MacGuffin'. It is the mechanical element that usually crops up in any story. In crook stories it is always the necklace and in spy stories it is always the papers.