The chapter classifies in two directions. Genres are sorted by their core promise, the payment a reader is guaranteed at the end, because that is what a book must keep or visibly decline; series are sorted by what a single volume closes and what it carries, because that is what a writer must decide before the second volume exists.
Five core promises
Most genres a novelist works in make one of five core promises. The list is a revision instrument, not a map of the bookshop: a shelf label may cover two promises, and a single promise may serve several shelves.
The promise of solution belongs to the mystery in all its forms, from the country-house puzzle to the police procedural. The book poses a question of fact, usually who did it and how, and guarantees that by the end the question will be answered from evidence the reader has been shown. Its obligatory scene, the scene its readers expect to see and miss if it is absent (the term is Shawn Coyne’s, in The Story Grid, 2015), is the exposure: the moment the answer is stated and the evidence is seen to support it.
The promise of union belongs to the romance. The Romance Writers of America defined a romance by two elements, a central love story and an emotionally satisfying and optimistic ending, and Pamela Regis’s A Natural History of the Romance Novel (2003) found eight elements in the form, from the meeting and the barrier to the declaration and the betrothal. Its obligatory scenes are the meeting and the declaration, and between them the point at which the union seems impossible, which Regis calls the point of ritual death.
The promise of the threat met belongs to the thriller, the horror novel and the adventure. A danger to the protagonist, and often to many others, is established and will be confronted directly by the end; the reader is guaranteed the confrontation, not the protagonist’s survival. Its obligatory scene is the hero at the mercy of the threat.
The promise of the kept rule belongs to science fiction and fantasy. A world that differs from ours is declared, and the book guarantees that it will obey the rules it has declared, so that a problem is solved within the world’s terms rather than by a new power arriving to solve it. Its obligatory scene is less fixed than the others’; most often it is the scene in which the world’s rule is seen to cost someone something.
The promise of significance belongs to literary fiction, which has conventions of its own and readers who notice when they are broken. The book guarantees that its particulars will add up to more than a summary of its events could hold, and that the ending will change how the reader sees what came before, whether or not it pays any of the other four. Its conventions include the open or partial ending, the domestic scale and the epiphany, and its obligatory scene is the recognition, in the sense The Reveal (Chapter 15) uses: the moment a character or the reader sees what the book has been about.
The table sets the five side by side with the convention each genre most often declines while keeping its promise, since that is where a writer has room.
| Core promise | Genres | Obligatory scene | Convention often declined while the promise is kept |
|---|---|---|---|
| Solution | Mystery, detective, procedural | The exposure | The detective’s survival, or the culprit’s punishment |
| Union | Romance, romantic comedy | The declaration | A wedding; the union may be a beginning |
| The threat met | Thriller, horror, adventure | The hero at the mercy of the threat | The hero’s survival, or a clean victory |
| The kept rule | Science fiction, fantasy | The rule’s cost seen | An explanation of the rule’s origin |
| Significance | Literary fiction | The recognition | Any of the other four payments |
The last column is the practical one. A mystery can let its culprit go free and keep its promise, because the promise was the answer, not the arrest; a romance can end on the first night of a relationship, because the promise was the union, not the marriage. A book that declines the core promise itself has done something larger, which the chapter calls a declined convention of the first rank, and The Mechanism says what such a decline requires.
Hybrids, modes and the dual timeline
A hybrid makes two core promises and keeps both: romantic suspense guarantees the threat met and the union, and its readers will accept neither without the other. A book in a mode, by contrast, borrows conventions without the core promise. The household novel is a family novel in the mystery mode, and its revision problem in The Problem is that its draft jacket sold the mode as a promise.
One genre takes Non-linear and Multi-timeline Architecture’s architecture (Chapter 8) as a convention. The dual-timeline mystery, of which Kate Morton’s The Forgotten Garden (2008) is an example, braids a present-day investigator with a strand in the past, and its readers expect the strands to converge by identity, a person in the present found to be the child or descendant of a person in the past. In such a book the braid is not a choice the arrangement must justify to the reader; it is a promise, and the convergence is its obligatory scene. Non-linear and Multi-timeline Architecture’s tests (Chapter 8) still apply to each strand’s question, but the necessity test is answered by the genre before the book begins.
Four forms of series
Series differ in what one volume closes and what it carries forward. The four forms below are distinguished by those two things, and the form a series declares in its first volumes is itself a promise about the rest.
The episodic series closes everything in each volume and carries forward only its hero, his world and his rule. Its volumes can be read in any order, and its hero usually has the steadfast arc of Arc and Theme (Chapter 12): Lee Child’s Jack Reacher arrives in a new town, the town changes, Reacher does not. Eco’s iterative scheme describes the form, and its pleasure is the variation within the scheme.
The episodic series with a running arc closes its volume question each time and carries a second line, a relationship or a past, that advances a step per volume. Its volumes can be read singly but are better read in order. The X-Files (1993–2002) alternated self-contained cases with episodes that advanced its continuing story, and many crime series now give the detective a life that changes across the books while the cases close.
The serial is one story published in volumes. Each volume closes a stage, not the story, and the reader must read in order; the series question is the story’s own. Elena Ferrante’s Neapolitan novels (2011–14; translated by Ann Goldstein, 2012–15) and Hilary Mantel’s Cromwell trilogy (2009–20) are serials, and J. R. R. Tolkien’s The Lord of the Rings (1954–55) is a single novel its publisher divided into three.
The relay series keeps a world and passes the centre from one character to another, so that each volume has a different protagonist, often a minor figure in the one before. Anthony Trollope’s Barsetshire novels are a relay, and so is Tana French’s Dublin Murder Squad, whose second novel, The Likeness (2008), is narrated by Cassie Maddox, the partner of the first book’s narrator. Its volumes close their own questions, and what carries is the place and the reader’s knowledge of people the new protagonist barely knows.
The table compares the four by the decisions a writer must make before the second volume.
| Form | What a volume closes | What carries | Reading order | The hero’s arc |
|---|---|---|---|---|
| Episodic | Everything | The hero and his rule | Free | Steadfast |
| Running arc | The volume question | One line, a step per volume | Preferred | Slow, staged |
| Serial | A stage | The story | Required | Any, across the whole |
| Relay | The volume question | The world and its people | Free, with rewards for order | A new protagonist each time |
Mixed forms are common, and the commonest revision problem in a series is a form changed without notice: an episodic series that ends one volume on an open question, or a serial whose middle volume closes so completely that the next must invent a reason to go on. Diagnostic Tests read both, and the full treatment adds the anthology and the prequel.
See also: the full treatment, section 3, with each promise’s conventions listed and a summary table of the series forms.