When a reader (whether a beta reader, or a literary agent or publisher, or hopefully a real-life genuine member-of-the-public reader) - picks up your book, you literally have only seconds to impress him or her.
There is so much competition for that reader's attention - whether it's the slushpile, (in the case of agent or publisher) or all the other books in the bookshop (in the case of the end-use reader).
And so, he or she will only allocate a very short period of time - maybe as few as thirty seconds! - to deciding if your work is worth reading.
Therefore, your job as the writer is to make absolutely sure that the answer to that question (“Is it worth my while reading on?”) is an absolute categorical 'yes!' - and the narrative hook is one way to do that.
The most popular way to use a narrative hook - and the easiest to carry off too - is to pose a question in your reader's mind, so that she just has to read on to find out the answer to that question.
There are two options here. The first is to pose the dramatic question early (e.g. Will the hero save the world?). The reader will have to read the whole book to find out the answer to that one!
The other option is to pose a smaller question (examples are given below, in the list of opening lines of famous novels). And, of course, by the time you've provided the answer to that question, you'll already have posed another question to keep her reading to find out that answer, and so on. As I often say: a writer's first job is to keep her readers reading!
Popular advice is to begin in medias res, which literally means in the middle of things. This surely has the advantage of intriguing and hooking the reader. It's not without its difficulties though, as whatever happened to get the characters in that situation then becomes back-story with all the challenges that entails."
excerpt from: www.fiction-writers-mentor.com/narrative-hook.html
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