Where the term comes from
Wikipedia defines a plot hole as an inconsistency in a storyline that goes against the flow of logic established by the plot. It says plot holes are usually unintended, often arising from editing or from writers forgetting that a new event contradicts earlier ones, and that audiences sometimes disagree on whether something counts as an error. It lists several types: factual errors, impossible events, out-of-character behaviour and continuity errors.
The worry itself is older than the phrase. In his Poetics, Aristotle praises Homer for building the Odyssey around a single action instead of including every adventure of Odysseus, such as incidents between which there is no necessary or probable connection. He also says the events of a plot should follow by the law of probability or necessity. A plot hole is a place where that connection fails.
An example
Cormac Ibarra writes a heist novel in which the vault at the Meridian Bank needs two keys held by two different officers. In chapter three, the heroine, Ilse Varga, steals one key and the officer is arrested. In chapter nine she opens the vault with that single key and nobody mentions the second. Beta readers keep writing the same note in the margin. Cormac fixes it by adding a scene in which Ilse discovers that the second officer's key was duplicated years earlier for a retirement gift, and it gives the plan a new risk. The hole was a continuity error; the fix turns it into a plot point.
Common mistakes
- Relying on a coincidence to get a character out of trouble when the earlier rules say they should be stuck.
- Letting characters forget what they know because the plot needs them ignorant.
- Changing the rules of a world, a timeline or a technology between chapters.
- Treating every unanswered question as a hole. A mystery the story chooses to leave open is different from a contradiction.
- Patching one hole with an explanation that creates a second one.
How to check your manuscript
Make a list of every rule, date and piece of knowledge your story relies on, then read your draft once looking only for contradictions. Trace each key decision and ask why the character would not have taken an easier route. Fresh readers are especially good at spotting gaps you have stopped seeing. For related terms, see deus ex machina, red herring and subplot.
In Musael, continuity checks follow who knew what and which scene taught it to the reader, which helps catch a character acting on something they have not learned yet.