MacGuffins

Definition

A 'MacGuffin' is a plot device which acts as a goal or motivating object/person in a film. Sometimes it can be the most vital part of a film's storyline but it is the effect of the McGuffin on the characters and motivation which is what makes it important. It leads a film from one part to the next and helps the story keep moving.

Commonly the MacGuffin is focused on in  a film in the first act, and after this becomes less important. A lot of the time they reappear towards the end of the film (or in the third act) and help the problems which have arisen in the film become resolved.

Example

For example in "The Shawshank Redemption" the central MacGuffin could be seen as the pick. This is because early on in the film it's introduced and helps Andy and Red become familiar with one another, developing the characters relationship. Although the pick is prominent throughout the film, it declines in importance because the viewer assumes Andy is just using it to carve small rocks. It regains importance towards the end of the film however when we discover that Andy has actually been using it to escape prison - a big twist on the film which is unexpected and resolves the main issue (Andy's innocent).