The final book in Gina Damico's Croak Trilogy, picks up right after the events of Scorch. Lex and her companions are still on the run as the Grimosphere's hate of them grows. They now have Grotton, the most powerful Grim of all times, in tow. They have to fix his mistakes or the Afterlife will be destroyed along with all of the souls. 
 I would definitely suggest reading this back to back with Scorch. The author does not give very much recap and secondary characters blur together. There are just so many people. I couldn't keep track and I didn't really care to. The end packs a wallop, but the rest was just ok. Uncle Mort and Driggs are still awesome. Lex is even tamer in this book than the previous ones (understandable since guilt is eating at her).