Main Characters: All the folks from the first two books, with a few minor exceptions (the old Inquisitor was killed at the end of the last book).
Amatis Herondale: Luke’s sister. Luke wasn’t always a werewolf and we find out what happened to turn him into a werewolf in this book.
Aline Penhallow – another youth Shadowhunter.
Sebastian Verlac – turns out to be the bad guy. And he’s Clary’s real brother. And he’s evil, evil, evil. And working with Valentine. He is the real Jonathan, pretending to be Sebastian. And Jace isn’t really Jonathan but a Herondale.
Max – we sort of met him in the second book. Here, he is very important. Right up until Sebastian kills him.
Main Premise: Picking up where we left off, we are headed to the Shadowhunter’s homeland to try to convince the Counsul and the other Shadowhunter’s of the trouble with Valentine and how to stop him. The angel Raziel, who Valentine thought he was serving, is called, bound to Clary, and the angel repudiates Valentine then kills him. Jace and Clary are both ultimately saved.
Locations: Alicante – the Shadowhunter’s homeland
Other Important Things to Remember for Later: Jace’s father was Stephen Herondale (and the prior Inquisitor who dies in the last book, Imogen, was Jace’s grandmother). Isabelle kills Sebastian. Clary finds an important spell book. Sebastian wasn’t really Sebastian, he was simply masquerading as Sebastian and is in fact Clary’s brother. Clary helps protect Simon by drawing the Mark of Cain on him, the first mark of that kind and its extremely powerful, and it was originally a curse. It is confirmed that Simon can walk in the sunlight becuase of Jace’s blood – and the unusually high angel content of Jace’s blood. Raziel, the angel who created the Shadowhunters, is who Valentine tried to summon. Raziel, however, kills Valentine because he sees what is going on. And he saves Jace – since Jace had technically died. Luke and Jocelyn finally get together. Alec and Magnus finally stop fighting their attraction. Simon and Maia… they all pari off very nicely. The downworlders and the Shadowhunters seem to be coming to terms with each other as a hole, and it looks like it’s just the bad downworlders who will need to worry about the Shadowhunters in the future. Most of the loose ends were tied up, so it was sort of surprising to see that there will be a book 4.
Tessa, from the Infernal Devices, can be seen talking to Magnus in the epilogue. We don’t really know much abut it, other than the author confirmed that it is in fact Tessa.
A family tree would have been helpful. But oh, well. Hopefully, we won’t need it for book 5!