The story of Clary Frey continues. 
 She decided to quit the Shadowhunter world one and for all, but how can she really quit when her best friend is now a Vampire and her father figure is a Werewolf and mystirious things keep happening that she can't ignore? 
 From the start of the book we see how the Lightwoods react to the fact that Jace is Valentine's son. 
 Which spoiler alert, is not good. 
 They belive that Valentine send his son to spy on the Lightwoods and they react by "kicking him out" of the institute. 
 Then we have Clary and Simon who out of the blue starting a relationship, 
 because Jace is Clary's brother so they can't happen obviously (we all kept shipping them, even tho it was kinda wrong), and because she basically feels bad for Simon and hopes that by pushing herself, she starts to like him otherwise than as a friend. 
 Sidenote When someone doesn't tickle your fancy, when you just don't like someone as more than a friend or at all, Don't push yourself into liking them! The only thing that will come out of it will be brocken hearts. It's not fair for either one of you. 
 Back to the book.... Jace get's thrown out on the streets and ends up at Luke's Werewolf bar when a young Werewolf gets killed and it appears that someone's attacking children from each Downworlder species and drains them of their blood. 
 So after Jace get's send to the City of Bones to spend the night as a prisoner by the inquisitor (because she belive's he's a spy for Valentine), the Silent Brothers get killed and The Mortal Sword get's stolen by Valentine and it turn's out that he was behind all the killings. 
 After that Simon and Maia gets abducted and Clary with Jace,Magnus and Lukes go on a rescue mision for him on Valentine's boat. 
 And while they try to save Simon and Maia, other Shadowhunters arive to kill Demon's and to get Valentine. 
 Long story short.... Valentine escapes, Simon and Maia are alive, Clary discovers that she has a special ability with runes and ends up sinking the boat with all the demons on them. 
 At the ending it turns out that the Lightwoods send Jace away so the inquisitor didn't find him and they love him just as much as their own. 
 In the end, end a woman tells Clary that she knows how to wake up her mother.