The working definition
The middle of a novel runs from the first commitment the beginning cannot take back to the point at which the ending’s movement starts. The first boundary is a change of state rather than a page: the protagonist has chosen, or been forced, into the line of action the book will follow, and the opening’s normal is no longer available. Screenwriting manuals call it the first turning point or the first plot point, and it is the moment at which the book’s question becomes specific. The second boundary is the start of the ending in the sense The Ending (Chapter 16) gives the word, the climax and its aftermath: the middle stops where the sequence that leads straight into the climax begins.
Defined by its boundaries, the middle is usually the largest part of a book. In the three-act convention of screenwriting, the middle, Act Two, takes about half the running time, 60 pages of a 120-page screenplay in the most widely taught version. Novels vary more, and a middle of half to three-fifths of the book is common, but the proportion follows from where the commitments fall and is not a target. The household novel’s middle runs from the drawer at about a quarter to Dov’s chapter at about 78 per cent, so it occupies 78 − 25 = 53 per cent of the book.
The turns inside it
A middle is not a level stretch between two turns. It has turns of its own, and the one that carries most weight is the midpoint, a turn near the centre that changes the protagonist’s relation to the goal. It can change the goal itself, change what the protagonist knows about the goal, change the protagonist’s mode, from reacting to what the opposition does to acting against it, or reverse the protagonist’s fortune. The name records a convention of placement, and a midpoint at 40 or 60 per cent is still a midpoint if it divides the middle into a half that asks one question and a half that asks another.
Two further words describe what happens between the turns. A complication is anything that stands in the protagonist’s way: an obstacle, a refusal, a delay. An escalation is a complication that changes what the protagonist can do or what doing it will cost. Every escalation complicates, but not every complication escalates, and the difference between the two is the subject of The Mechanism. Aristotle’s word for the part of a plot before its turning point, the desis or tying of the knot, covers both, which is one reason the distinction is easy to miss.
Adjacent terms
Several neighbouring words describe the same stretch from other angles. Act Two is the screen form’s name for it and brings the three-act model with it, which suits many novels and not all. Rising action is the English name for the second of the five parts in Gustav Freytag’s pyramid of dramatic structure, set out in How It Works, where the climax sits in the middle of the play rather than near its end. Sagging middle is a workshop term for the reader’s experience of a middle that has stopped moving; it names a symptom and not a cause, and a sagging middle can have any of the causes in Failure Patterns. The development, a term from music, is the central section of a movement in sonata form, in which themes stated in the opening section are broken up and carried through other keys before they return. It is a useful analogy, since a strong middle mostly works on material the beginning has already introduced, which is also why the middle is where the plants of The Ending’s plant audit (Chapter 16) are maintained.
What the chapter leaves to other chapters
The escalation of a single sequence of scene and sequel belongs to Scene and Sequel (Chapter 2), and the alternation of plot lines across the middle to The Subplot (Chapter 14). The inner change a protagonist undergoes in the middle is traced across the book in Arc and Theme (Chapter 12); a midpoint that is a revelation is a reveal, and its management belongs to The Reveal (Chapter 15). A middle told out of chronological order belongs to Non-linear and Multi-timeline Architecture (Chapter 8). The middle volume of a trilogy or series belongs to Series and Genre (Chapter 17), and the order in which to revise the parts of a book belongs to The Structural Edit (Chapter 18).
See also: the full treatment, with a table comparing where the screenwriting manuals place the middle’s boundaries and turns.