How to Write a Book Series, Step by Step

To write a book series, decide whether it is one story told across several books or a run of complete stories with the same characters, give every book its own question and its own ending, run one larger series question underneath all of them, and keep a series bible so that names, ages and rules stay the same from book to book. The craft of each book is the craft of any novel. What a series adds is the second layer, and the record that holds it together. The steps below take both in turn, with what Arthur Conan Doyle, J. R. R. Tolkien and Agatha Christie actually wrote about their own series, checked in their memoirs and letters.

What Is a Book Series?

A book series is two or more books that share characters, a world or a continuing story, written to be read as a set. Every series makes one choice before any other: does each book stand alone, or does each one end with the story unfinished?

Arthur Conan Doyle made that choice on purpose, and his reasoning is still the clearest statement of it. In his memoir Memories and Adventures (1924) he describes the magazines of the 1890s: "it had struck me that a single character running through a series, if it only engaged the attention of the reader, would bind that reader to that particular magazine. On the other hand, it had long seemed to me that the ordinary serial might be an impediment rather than a help to a magazine, since, sooner or later, one missed one number and afterwards it had lost all interest."

His answer: "Clearly the ideal compromise was a character which carried through, and yet instalments which were each complete in themselves". That character was Sherlock Holmes.

What Are the Types of Book Series?

There are four, and they differ in one thing: how much of the story carries over from one book to the next.

Type	What carries over	What each book closes	Examples
Serial	One story, split across books	Very little; the story ends in the last book	The Lord of the Rings
Episodic	The main character	Its whole plot	Sherlock Holmes, Hercule Poirot, Jack Reacher
Hybrid	The character and a series arc	Its own plot, while the series arc moves on	Most modern fantasy and crime series
Shared world	The setting	Its whole plot, often with a new lead	A romance series with a new couple in the same town each book

An episodic series can be read in any order. The official Jack Reacher site says exactly that: "The Jack Reacher books can be read in any order, but here they are in the order in which they were written." A serial has to be read in order, because each book is a part of one book. Most series published now are hybrids: every book is complete, and something bigger moves forward underneath.

A note on the words: some guides use "episodic" for a series that tells one continuing story. That is the opposite of what the word means. An episode is complete in itself, which is Doyle's "instalments which were each complete in themselves". A story that continues is a serial.

What Are the Steps to Write a Book Series?

1. Choose the type of series.
2. Find the series question and the book questions.
3. Plan the series arc across the books.
4. Make Book One complete on its own.
5. Plan each book's own arc.
6. Start a series bible on day one.
7. Write the middle books so they move the series.
8. Plan the ending of the series.

Step 1: Should Your Series Be Serial or Episodic?

Choose by the story you have. A single huge conflict that cannot be settled quickly, a war, a quest, a rising sea, wants a serial or a hybrid. A character who solves a new problem every time, a detective, a doctor, a fixer, wants an episodic series. A place where many stories could happen wants a shared world.

Think about the reader too. Doyle's point is still true of books: a reader who misses a book in a serial is lost, and a reader who starts an episodic series at book five is fine. A serial asks more of readers and gives more back at the end.

Step 2: What Is the Difference Between a Series Arc and a Book Arc?

A book arc is the story of one book: a question raised near the start and answered at the end. A series arc is the story of the whole series: a larger question raised in Book One and answered only in the last book.

Write both down as questions before you plan anything else.

• The series question. Will Mara save the town from the rising sea?
• Each book's question. Who rang the drowned bell? Can Mara take the salt crown from the queen? What will she give to stop the last tide?

Each book answers its own question. The series question stays open until the end, and every book moves it one step. That is the whole design of a hybrid series in two lines, and the test for any book in it: if the book's question is not answered by its last page, the reader feels cheated; if the series question has not moved, the book feels like filler.

Characters have arcs at both levels too. A protagonist can change a little in each book and a great deal across the series. The shapes a change can take are set out in character arc types.

Step 3: How Do You Plan a Series Arc?

Plan the end of the series first, then the steps that lead to it. You need to know where the series question is answered, and in which book, before you write Book One, or Book One will make promises the series cannot keep.

How much more to plan depends on how you work. A writer who outlines will sketch every book's main turn. A writer who discovers the story as they go can still fix the end point and the order of the big reveals, and leave the rest open. The two approaches are weighed on plotter vs pantser.

Tolkien is the warning about a serial planned as one book. The Lord of the Rings is usually called a trilogy, but he did not call it one. In a 1955 letter to his American publisher, Houghton Mifflin (Letters, no. 165): "The book is not of course a 'trilogy'. That and the titles of the volumes was a fudge thought necessary for publication, owing to length and cost. There is no real division into 3, nor is any one part intelligible alone." It was written as one novel and split for publication. The only natural divisions, he added in the same letter, were "the 'books' I-VI", six books, not three. A book that cannot be read alone is fine when the volumes come out together. It is a risk when the second book is a year or more behind the first.

Step 4: Does Book One Need to Stand Alone?

Yes. Book One has to work as a complete novel, with its own question answered at the end, even in a serial. Readers decide whether to buy Book Two on the strength of Book One, and an agent or publisher considering a debut is buying one book, not a promise of three.

So close Book One's own story fully, and leave the series question open in a way the reader can feel. Do not save your best idea for a later book that may never be written. A series is built from books that each earn the next one.

Step 5: How Do You Plan Each Book in a Series?

Like any novel, with one extra job. Each book needs its own protagonist goal, its own escalating obstacles and its own climax. The extra job is to move the series arc, so each book should end with the world or the characters changed in a way the next book has to deal with.

Each book can carry the series arc as a subplot that runs under the main plot and comes to the surface at key moments. In the last book, the series arc becomes the main plot.

Each later book also has to work for a reader who has forgotten the one before, or never read it. Remind them of what matters in a line or two, inside a scene, when it first counts, rather than opening with a summary of the last book.

The steps for the novel itself, from premise to revision, are on how to write a novel.

Step 6: What Is a Series Bible?

A series bible is the record of everything a series has established: every character's name, age, appearance and history; every place and distance; every rule of the world; and the timeline of events across all the books. It is the story bible of a single novel, kept up across the whole series.

Start it with Book One. A series is where small decisions come back years later. Agatha Christie shows why in her Autobiography (1977). When she invented Hercule Poirot, she decided he would be "A retired police officer. Not too young a one. What a mistake I made there. The result is that my fictional detective must really be well over a hundred by now." She wrote about Poirot for more than half a century, and his age, fixed in the first book, could never change. A series bible will not stop a choice like that, but it puts it in front of you, with the date and the age beside it, before it becomes a problem.

Record more than you think you need: eye colours, the name of a minor character's dog, the year a war ended. Readers of series remember these things better than writers do. The ways mismatches creep in are covered in how to catch continuity errors.

Step 7: How Do You Write the Middle Books of a Series?

Make each middle book change something that cannot be undone. Middle books are the hardest in a series, because the series question cannot be answered yet. The risk is a book where the characters travel, fight and talk, and the series ends up exactly where it was.

Three things keep a middle book moving:

• A complete book question. It needs its own ending, as much as Book One did.
• A turn in the series arc. A reveal, a loss or a victory that changes what the series question means.
• A change in the protagonist. By the end, they are a different person from the one who began the book.

Step 8: How Do You End a Book Series?

Answer the series question, and answer it with what the books have built. The ending of a series carries the weight of every book before it, so the forces, rules and choices that settle it should already be on the page. A last-minute rescue reads as a cheat after one book. After five, it reads as a betrayal.

Plan the ending early, and know how many books it takes. A series that keeps going after its question is answered tends to lose readers. A series of episodes can run as long as there are cases, but a serial or hybrid ends when its question does.

What Did Conan Doyle Say About Killing Sherlock Holmes?

He wanted to stop writing them, and he said why. A common story is that Doyle simply hated Holmes. His own account, in Memories and Adventures: "after I had done two series of them I saw that I was in danger of having my hand forced, and of being entirely identified with what I regarded as a lower stratum of literary achievement. Therefore as a sign of my resolution I determined to end the life of my hero."

He sent Holmes over the Reichenbach Falls, "fully determined that he should stay there--as indeed for some years he did." Then he brought him back. It is the most famous lesson in series writing: an episodic series belongs to its readers as much as to its author, and they will not always let a character go.

Which Series Claims Are Wrong?

• "The Lord of the Rings is a trilogy." Tolkien wrote that it is "not of course a 'trilogy'", and that the three volumes were "a fudge thought necessary for publication, owing to length and cost."
• "Episodic means one continuing story." It means the reverse. Doyle's model, a character who carries through and "instalments which were each complete in themselves", is the episodic series.
• "Doyle invented the series detective." He did not, and he did not claim to. Edgar Allan Poe's detective C. Auguste Dupin had already appeared in three stories in the 1840s. What Doyle claimed was the magazine plan, one character carried through and a complete story in every issue: "I believe that I was the first to realize this and 'The Strand Magazine' the first to put it into practice."
• "Doyle killed Holmes because he hated him." His stated reason was that he did not want to be "entirely identified" with work he thought lesser.

A Worked Example

Here is the plan for a hybrid trilogy, The Tide Books.

• Series question: will Mara save the town of Fenwater from the rising sea?
• Book One, The Bell. Book question: who rang the drowned bell in the harbour? Answer: the salt queen, to call the sea in. Series step: Mara learns the sea is being called, not rising by itself.
• Book Two, The Crown. Book question: can Mara take the salt crown from the queen? Answer: yes, but the crown cannot stop the tide. Series step: the town turns to Mara to lead it.
• Book Three, The Tide. Book question: what will Mara give to stop the last tide? Answer: the crown and her place in the town. Series answer: Fenwater is saved.

Each book ends. The series question moves one step each time. And Mara changes at both levels: she learns to trust in Book One, to lead in Book Two, and to let go in Book Three.

How Do You Plan a Book Series in Deckle?

Deckle is a novel-writing app for Windows, macOS and Linux. Its Binder holds the book's parts, chapters and scenes, its Outliner is a board of cards, one for every document, each with a synopsis, and its Codex holds characters, places and rules beside the manuscript. A series can be kept in one project for all the books, or one project per book.

One project for the whole series:

1. In the Binder, click Add to Draft (the + beside Draft) and choose Part. Make one Part for each book, and name it with the book's title.
2. Right-click each Part and choose Make This a Separate Book. Each book's chapter numbers start again at one, its running heads carry its title, and the ebook's contents list it as a book with its chapters underneath.
3. Open the Outliner on the Draft. Each book is a card. In each card's synopsis, write the book's question and its answer, and the step the series question takes.
4. Open the Codex from its button in the menu bar. Under Characters, click the + and choose Character. Write the series arc in the Arc section, book by book.
5. Click an entry's Mentions tab to see every chapter that names it, in manuscript order, across all the books. That is where a changed eye colour or a wrong age in Book Three gets caught.

One project per book: finish Book One, use Export as Template on the File menu, and start Book Two with New Project and From Template File. The Codex, styling and Binder structure carry over, and Book Two gets its own copy of the series bible. The steps, and the one thing to clear first, are in setting up a series template.

One project suits a series written ahead and kept consistent in one place, or published as a boxed set. One project per book suits a series released book by book.

Common Mistakes

• A Book One that does not end. If its own question is not answered, there may be no Book Two to read.
• No series question. Books that share only a character and nothing changes between them are an episodic series. That is fine, if it is a choice.
• Middle books that tread water. Each one needs a book question answered and a series turn that cannot be undone.
• Keeping the series bible in your head. Ages, dates and spellings drift across books written years apart. Write them down from Book One.
• Fixing details you will regret. Christie's elderly Poirot is the warning. Think about ages and dates over the whole series, not just the first book.
• Calling a serial "episodic". Readers choose books by this. An episodic series promises they can start anywhere.
• Planning more books than the story holds. A series should end when its question is answered.

Sources

Retrieved 30 October 2026.

• Arthur Conan Doyle, Memories and Adventures (1924), on the Strand stories and on Reichenbach (Project Gutenberg).
• Humphrey Carpenter (ed.), The Letters of J. R. R. Tolkien (1981), no. 165 to the Houghton Mifflin Co. (1955), postscript, read through Open Library's search inside (archive.org).
• Agatha Christie, An Autobiography (1977), on choosing Poirot, read through Open Library's search inside (archive.org).
• Jack Reacher official site, Books in order: "The Jack Reacher books can be read in any order".
• Edgar Allan Poe Society of Baltimore, The Murders in the Rue Morgue, the first Dupin story (1841).