In medias res
In medias res is the literary and artistic narrative technique of starting right in the middle of a dramatic or action packed event. An in medias res narrative structure will often rely on flashbacks and other forms of non-linear storytelling in order to fill the audience in. To be considered in medias res, a story cannot simply have prequels or a back-story that has not yet been told. It must start in the middle of a climactic, dramatic, or action packed event.
In medias res has origins in oral tradition, and is a common convention of epic poetry, but can be found in a wide range of genres.
Why Is It A Trope?
In medias res is a trope because it is a significant and recurring feature or structural device that can be found in all sorts of narratives. It is especially common in oral traditions and epic poetry, where it is considered by many to have originated as a convention.
Commonly found in
Star Wars Episode IV, A New Hope begins in medias res, opening in the midst of a space battle between the rebel and imperial starships.
Homer's Iliad opens in medias res, starting in the midst of the Trojan War.
Wikipedia - In Medias Res