I liked the conclusion of this series. 
 The third book picks up almost where the last one left off, with Sophie stepping into the Itineris trying to get to her mom. When Sophie emerges from the Itineris she discovers she lost 17 days. She is still unsure if anyone survived the fire at Thorne Abbey. She manages to locate the Brannicks or rather one locates her and she learns a thing or two. One of the things she learns is that she is the only one powerful enough to stop the Casnoffs, but at the current moment Sophie is unable to access her powers. There is a way for Sophie to regain her powers through the grimoire, but that is at Hex Hall with the Casnoffs. 
 I liked the adventure they go on in this book, but at the same time there are some things I didn't like. 
 SPOILER ALERT 
 One of the things I did not like is when one of the main characters sacrifices themselves for Sophie at the end. I definitely understand how is is the ultimate sacrifice and let me and Sophie know exactly how much this person loved her, but I am sad they didn't get the happy ending I wanted for them. I guess based on the person's ghost we see at the end, we can tell they get some measure of happiness? 
 END SPOILER ALERT 
 I will say that out of the three books, this one is my least favorite, but I still liked it. I look forward to reading more books my Rachel Hawkins.