A MacGuffin is an object, event or character that sets the plot in motion and keeps characters chasing it, even though it matters little in itself and could be swapped for something else.
Where the term comes from
Britannica describes a MacGuffin as an element in a work of fiction that drives the plot and motivates the characters despite being relatively insignificant to the story. It associates the word with the filmmaker Alfred Hitchcock, while noting that some film fans credit the screenwriter Angus MacPhail with coining it. Merriam-Webster tells the story Hitchcock borrowed: a passenger on a train says the odd package he carries holds a MacGuffin, used to catch tigers in the Scottish Highlands, and when told there are no tigers there, he replies that then it must not be a MacGuffin. The joke is the point. What the package holds hardly matters. What matters is that people want it.
An example
In a fantasy novel, Corwen Ashby, a cartographer, is hired to recover the Saltwife Ledger from a drowned archive. Rival guilds, a smuggler and a disgraced magistrate all chase it. By the end we learn the ledger is a list of tide tables, and nobody cares, because the chase has changed everyone in it. The ledger could have been a ring, a letter or a child's drawing. The story is about the loyalties that break while people pursue it.
Common mistakes
- Making the MacGuffin so vague that readers cannot tell why anyone wants it. It can be unimportant to the story, but it must be important to the characters.
- Explaining it too late. If the stakes only appear in the final chapters, the middle of the book has nothing pulling the plot forward.
- Mistaking it for the theme. The object is a trigger. The meaning of the book lives in what the pursuit does to the people.
- Letting it vanish with no answer at all. Even a hollow MacGuffin deserves a clear moment where the characters see what it is.
How to check your manuscript
Write down in one sentence what your characters believe the object is worth. Then ask whether the plot would still run if you replaced it with something else. If it would, you have a working MacGuffin, and you can put your effort into the people chasing it. If the story collapses, the object is probably carrying theme or character work and is better called the center of the book. Also check that the want shows up early, within the first act, since an early want is what keeps the middle moving. The story structure guide shows where that trigger tends to sit.