By a Thread is the first Elemental Assassin book where Mab Monroe doesn't play a major part - after all she's finally dead. I was really curious to read this book because it was going to be the book that decided whether or not this series could continue after the Mab storyline was over. What would Gin be up to now that her arch-nemesis is dead, she finally had her revenge for the death of her family, and Ashland is somewhat safe? Estep did an amazing job at finding a way to keep Gin's story going and making it feel perfectly natural. 
 Gin cannot stay out of trouble no matter where she goes and she managed to find quite a bit on her vacation. I loved getting to see these characters in a different environment. It was also nice to see Gin finally slowing down a little bit and acknowledging that she had some emotional issues, especially family issues, that she needs to deal with (the final scene with Gin and Bria literally brought tears to my eyes). Another great thing about this book is that it did tie up another loose end in the series as Gin finally got some closure on the Caine issue, so she can finally move on and look towards the future not the past. I'm hoping that future books will allow her to do that and won't dwell too much on issues that she overcame in this book. 
 My only complaint about this book in particular is that I wasn't sure about the big villain in this book, he was supposedly stronger than Mab Monroe was and because he was described to be that powerful his defeat seemed almost too easy. Not that Gin had an easy time but it seemed as though she just wasn't thinking through her plans as much. 
 As a generalization for this series; Estep recaps way too much. She recaps more than we need to know for each particular book, and then towards the end of the book she is recapping earlier chapters of the book. She also tends to use the exact same phrases which makes it seem as though she can just copy and paste some paragraphs from one book to another (for example, every time we are re-introduced to Finn we are told the same joke about how Gin can't believe some irate husband has not hired her to kill him yet). There are a lot of pages which I end up skimming or skipping because they are entirely made up of recaps. It just gets frustrating when the stories are so great that I want to dive right into them and instead every five minutes I'm dragged out of the current storyline into a long reminder about what happened in the last five books. 
 As always, Estep does a great job of making the big bad Spider into a real person who readers can easily sympathize with. The bad guys are so bad that you are happy to see them dead and gone. Overall, it was a fantastic installment in the series and I cannot wait for the next book to come out (especially after the teaser we were given in this one!).