_Darkest Edge of Dawn_: takes place pretty soon after the events of Book 1. The Ash production operation is shut down, and there's some reason to believe that the Darkness isn't actually going to actually spread or even last forever. However, just because Charlie dealt with one bad guy does not mean the evil from book one is completely dealt with. This outing deals with what the drug operation was really intended to accomplish, there's an Elysian serial killer on the loose, etc. The Dragon is Super Cool.
_The Hour of Dust and Ashes_: In this outing, Charlie has something new tailing her whenever she tries to use her power. It's pretty scary but not obviously damaging. To her. Charlie goes back to the Oracle who puts her in touch with the Sylphs to try to figure out who is controlling the Ash victims. When Charlie oopses and lets one of the victims know they've got a plan to actually figure out who/what is controlling them, antics ensue: Charlie, Hank, Rex and Brim all go to Charbydon to deal with a Situation, barely ahead of a kidnap squad looking for Hank because of involved-backstory-making-me-worry-a-lit
Characters do grow and change over the course of the books. The world building is not bad. Gay is having a ton of fun building sexual tension between Charlie and Hank. The development of the Sian character is tortuously slow, but I'm really hoping that will pay off at some point. I will continue to buy more books in this series; they are Candy.
ETA: If you've read the Elantra chronicles, some of the themes (female protagonist slowly turning into a divine being, writing on her body) are going to seem kinda familiar.