Okay kiddo, have you ever heard of a detective story where the detective has to solve a mystery? Well, an inverted detective story is kind of like the opposite of that. In this kind of story, you already know who the criminal is and what they have done, but what you don't know is how the criminal will be caught or what consequences they will face.
It's like, imagine you have a puzzle and you already have all the pieces, but you don't know how to put them together to create the final picture. That's what an inverted detective story is all about.
So, the story starts with a crime being committed and we know who committed the crime. But then, the rest of the story is about how the detective (or someone else) pieces together the evidence to catch the criminal.
It's like a game of chess, where both players know all the moves the other player can make, but the game isn't over until someone wins.
Overall, inverted detective stories give you a different perspective on the crime genre by focusing on the process of catching the criminal instead of just who did it.