You know how movie trailers will try to get you excited about the eleventy-billionth sequel by yelling "The stakes have never been higher!" Well, cheesy as it is, that's the exact truth about The Undead Pool. Demon and elven magic clash, the undead vampires' control over Cincinnati falters, and the elves have turned against Trent. As usual, Rachel is in the middle of it, and this time the cost of failure is her sanity--and the stability of the entire country. 
 Rachel's position as an in-between sort of person--daywalking demon, law-enforcement-adjacent, etc--is never more obvious or tenuous than in The Undead Pool. And it's that very liminality that makes her the focus of the elven magic, and means that she's the only one who can tame it. Yet the demons are terrified of it, and she risks losing her place as one of them, especially with her burgeoning relationship with Trent. 
 Every novel in this series is better than the last, and Harrison continues to pull together story threads that may have been put in place as early as the first book. Nothing is dropped or forgotten, and the final book in the series promises to be amazing.