What is one effect that an in medias res opening?

One effect of an in medias res opening is that it immediately throws the audience into the middle of the action, creating a sense of intrigue and urgency. By starting the story at a crucial moment or pivotal event, the audience is forced to piece together the context of the narrative through clues and information revealed later on in the story. This can heighten suspense, engage the audience's attention, and create a more dynamic storytelling experience. It also allows for non-linear storytelling, as the audience is gradually shown how the characters and events reached the point they are at in the opening scene.