What does "in medias res" mean?

First of all, let's address the elephant in the room. You don't need to do anything just because someone in a writing group told you to. Writing groups are for critique, and people can offer suggestions, but that doesn't mean you need to act on them. It's also okay to not know what something is, so you don't need to pretend in order to impress anyone else in your writing group. No matter how long you've been writing, there is always more to learn, and increasing your knowledge is only ever a good thing. Don't ever feel you need to be embarrassed about learning.

Now that's out of the way, let's move on to the meat of the question: in medias res.

What "in medias res" means

"In medias res" is Latin for "into the middle of things." It's a literary term for starting a story partway through the action, rather than at the chronological beginning of the story.

The term comes from classical epic poetry. In Homer's Odyssey, for instance, we learn about Odysseus's journey while it is already well underway. Odysseus is already held captive on Ogygia, Calypso's island, and the details of his earlier journey are revealed after this opening as experiences that preceded it.

In modern terms, it just means: start your scene where the tension already is, not at the chronological beginning.

Two recognisable examples might help make this easier to picture. In The Emperor's New Groove, we don't open with Kuzco going about his life as emperor before being turned into a llama. It opens with him already transformed, with his own narration interrupting to explain how he got there. To turn to literature for an example, Edgar Allan Poe's The Tell-Tale Heart opens after a murder has already happened, with the narrator mid-confession, insisting to whoever's listening that he isn't mad. Both drop you into a moment that's chronologically later than the "true" beginning of the story, and only fill in how everyone got there once you're already hooked and want to know.

Is it something you should be doing?

In medias res is a tool, not a requirement. Plenty of excellent novels open in medias res. But plenty of equally excellent novels open with a character experiencing their ordinary world. Neither approach is more "correct," they're just doing different jobs.

The reason it may have been suggested to you might not even be because you need to open in medias res, but because you need to open on a point of action. These are often conflated, but they aren't the same thing structurally. In medias res often forces you to start on an action beat, which isn't necessarily an easy fix, but it can at least patch over a slow opening. If you have an exciting part of your story ready to go, opening there and filling in the backstory as the narrative progresses can be a good way to start with a bang. That doesn't necessarily mean it serves the story, though. There are other ways to open with a character doing something active that still serve the story chronologically.

Basically, you need to decide on the kind of story you want to tell, and determine what serves it best. Does your story need to build naturally, on a chronological timeframe? Or will it be served best by throwing readers into the action and strategically revealing how they came to be in that moment?

When it's helpful, and when it's not

In medias res tends to work well when your story leans on momentum, tension, or a ticking clock (thrillers, action, high-stakes fantasy, for instance). That immediacy means you can put the reader right into the action and strategically reveal backstory when it's relevant. If you want to hook your reader before you ask them to sit through any setup or worldbuilding, then starting right in the middle of things is the right call. You might also want to tell your protagonist's story in a certain way, where they're one way at a specific point in the story, and the revelations are how they became that way. For instance, you might want to write a protagonist who is likeable, but you want the reader to think about them differently once they learn more (or vice versa).

You shouldn't use in medias res if chronology is important to the story you're telling. This is often true of stories with a strong sense of world and place that need to be established before the protagonist embarks on whatever physical or personal journey the narrative will take them on. You'll also need to weigh up genre conventions. Literary fiction, for instance, tends to focus quite deeply on character rather than plot, meaning it usually shows a personal progression that requires chronology. That's not to say you can't use in medias res against traditional genre conventions, but you do need to think about your readers and how they might respond. The other thing to consider is whether jumping into the middle of the action would confuse, rather than hook, a reader. If a reader needs context to understand what's happening in the scene, in medias res won't be helpful.

How to try it without confusing your readers

If you do decide an in medias res opening is right for your story, the risk isn't that it's the "wrong" choice, but that it's easy to do badly. Dropping a reader into total confusion without context is a trap that's easy to fall into.

Make sure you ground the reader in the moment without needing to give them the full context. Readers need to understand what's at stake, even if they don't understand how a character got to that point yet. It's also easy to fall into the dreaded info-dump at this point. If you worry that your reader needs context, it can be tempting to resort to the crutch of a sudden backstory reveal, rather than the gradual reveal that makes in medias res such a powerful storytelling tool. There's a whole approach to feeding in history without it turning into a lecture, and it applies just as much to a character's immediate backstory as it does to worldbuilding.

The biggest consideration is to make sure that something is genuinely at stake in your opening scene. Action without stakes is just noise. Your character needs a real goal, motivation, and obstacle from the very first page, which needs to be communicated even if they're already well into their journey.

Trust the story you're actually writing

The advice from your writing group is just that: advice. It's yours to take and act upon as you wish. And now that you're furnished with all the information about what in medias res is, it can hopefully help you make an informed decision about whether it's the right tool for your story. So with that in mind, you can go back to your story and ask the real questions: does your opening chapter hook your reader, does it serve your story, and would opening the novel at a later point in your character's journey actually help?