City of Glass is the third book in the Mortal Instruments series written by Cassandra Clare. The book continues is a continuation of the previous two and it follows Clary and Jace as they try to get past their romantic feelings that are inappropriate because of their brother-sister relationship. The Shadowhunters are forced to decide whether they would fight against Valentine or let him be their leader and even if for some characters the choice is obvious, some characters have doubts n whether to accept help from the Downworlders or just give in.
The book received mixed reviews but was generally well received by the fans of the book series. The book was published in 2009 and is the third book, being followed by another three published books.