I hadn't read this book earlier because my friend told me that it was just like The Mortal Intstruments but in a different setting, but after finishing City of Heavenly Fire and then reading lots of positive reviews about it I decided to finally read it.
I enjoyed this book, but didn't think it was significantly better than any of the books in The Mortal Instruments series which is how I've often heard this series referred to. I did enjoy it though, and if this book was just setting up the other two books in the series then I'm sure they'll be really good. I can see the similarities to The Mortal Instruments in that the basic starting plot is sort of the same, as a girl who doesn't know of her unique power in the shadowhunter world is found by shadowhunters and introduced to the institute where two teenage boys that are parabatai and one guarded female teenager live with two parents, but asides from that general setup it is a very different story. One thing I hope that continues with the other books is how the love triangle is playing out. I strongly dislike love triangles for the sake of love triangles but I appreciate that the one in this book seems important to the story, not just to have something for fans to fight about, and that it is done in a way that doesn't make me feel like I'm reading a love triangle until I reflect back on it. I thought that knowing the ending of this book from reading City of Heavenly Fire it would mean that I wouldn't enjoy the series, but I find it really interesting that so far it hasn't really bothered me and although it reveals who Tessa ends up with, and the outcome of Will, Tessa and Jem there are still a lot of plot points in the series that I don't know the outcome of. My favourite character in this book is Henry, he reminded me of Arthur Weasley which is probably why I like him so much, but he was also a really welcome change to all the other shadowhunters that are in this book and The Mortal Instruments series because he's so gentle.
Tessa Gray moves to London after her Aunt dies to live with her brother Nate but once there she is immediately taken captive by two warlocks known as the dark sisters, who teach her how to use her ability - to change into another person and access their thoughts - that she never knew she had. After six weeks she is rescued by Will Herondale and a few other shadowhunters from the London Institute. She agrees to tell them what she knows about what the dark sisters were doing if they agree to help find her brother who was taken by them. They soon learn that "The Magister" who the dark sisters answer to and who wanted to marry Tessa is DeQuincey, a vampire that is at the head of the Pandemonium Club, a club for downworlders and mundanes that hate Nephilim. For the Clave to act against him, they must witness him actually breaking the accords, so Tessa changes into Camille and she and Will go and see DeQuincey harming a mundane at one of his parties and the mundane turns out to be Nate. Nate then tells them that DeQuincey is binding the demon energies to his clockwork soldiers tonight, and when he gives them the address, the Clave rush off to battle him but leave Jem and Will behind as they are too young. Mortmain, Nate's former employer and the one that supplied the clockwork parts to DeQuincey, shows up at the Institute and tells Jem and Will that the dark sisters are at another address to DeQuincey doing the necessary spells to bind the demon energies so they leave to go kill them. The clockwork soldiers then break into the Institute and Nate turns against Tessa and tells her that Mortmain is the real Magister and he serves him. When Mortmain captures Jessamine and Sophie he tells Tessa that if she doesn't come with him he will kill them so she turns her knife on herself and tells him that she will kill herself if he doesn't answer her questions. He ignores her and she stabs herself, but when Will returns and finds Mortmain over her body covered in blood Mortmain disappears using a ring like the one Sebastian uses in The Mortal Instruments. When Will goes to cradle Tessa she is alive and tells him that just when she went to stab herself she changed into a girl the dark sisters made her change into who died of a gunshot wound and bled whenever she changed into her. Tessa then decides to stay at the Institute and help them, and Will goes to Magnus asking him for help with something unknown.