Book 4, starting from the end of the Brisingr with a focus on ExA, rated mature for later chapters, there will be warning before the chapter with mature themes, and right before the actual scene as well.

When Detective Rukia Kuchiki finds her brothers body in the slums she vows to find his killer, but when the murders continue she is forced to work with a Detective who can push all of her buttons. Will they find the killer or end up killing one other? IR