Jace and Simon cheat on izzy and clary. The girls leave town and come to a strange place Magnus and Alec are the only ones who know where they are and it really pisses jace off that they won't tell him where the love of his life is even though he nearly got killed my Alec and Magnus last time jace saw them 2 years ago and Simon is jaces only friend (ironic right?) if you haven't read the books there are a lot of references so yea read and find out who is more mad at jace Magnus or Jocelyn