Is there a formula for writing a book? Why do many books have similar plots?

The short answer is no. But there are some general rules that I think are worth following, and, to be honest, they’re pretty simple and common-sensical.

First of all, I believe you need a premise. I define the premise as the answer to the question: what is the story about? It should include a protagonist, a world and at least one plot point. That’s very basic, because it usually has a handful of characters, and possibly more than one plot point, and you may end up in more than one world, but I’ll get to all that.

Whether you outline or not, and in how much detail, is a personal proclivity. But here’s the thing: the simple 3 act structure of setup, development and resolution is a good starting point. At the end of the setup, the premise should be self-evident, otherwise the reader is left asking: what’s it all about? Examples: a boy learns he has to attend a wizard school; a young man, who lives on an isolated world, receives a distress call from a princess; a hobbit is given a mission by a wizard to take a long journey to destroy a magic ring. Note that there is a key plot point where all this is ‘learned’, by both the protagonist and the reader or audience (if it’s a movie). Notice also, that all these stories took the protagonist from one world into another. Would you say they have similar plots? I wouldn’t.

And this brings me to the next relevant point, which is the use of tropes. Tropes are shared a lot, which is perhaps where you get the idea that stories have similar plots. Typical tropes are: a fish out of water; a best friend becomes a love-interest; the hero’s journey; a master-apprentice relationship. My novel, Elvene, shares tropes with Hayao Miyazaki’s Nausicaa of the Valley of the Wind, which I saw (and read) after I’d written it. Some people have compared it to James Cameron’s Avatar, but I wrote it 6 years before, and it is a completely different story.

There are 2 conflicting goals in writing a story – to deliver on expectations and to create surprises. The expectations are formulated early in the story, without the need to spell them out, and the surprises come later, often in the resolution stage. Twists are good, but they need to be believable and consistent with everything that’s happened before.