From Wikipedia: A MacGuffin (sometimes McGuffin or maguffin) is 'a plot element that catches the viewers' attention or drives the plot of a work of fiction'. Sometimes, the specific nature of the MacGuffin is not important to the plot such that anything that serves as a motivation serves its purpose. The MacGuffin can sometimes be ambiguous, completely undefined, generic or left open to interpretation. The MacGuffin is common in films, especially thrillers.