City of Glass is the third and last book in the Mortal Instruments series. In the book Clary travels to Idris to find a warlock who can wake up Clary's mother, but Jace doesn't want her to go.Once she gets to Idris Clary gets ill and is taken in by Luke's sister. After sneaking out of Luke's sister's house she meets up the Lightwoods and Jace, but receives something less than a warm welcome. Also she meets the Shadowhunter named Sebastian who tells her he will help her find the warlock she is looking for. But events come to unfold and Sebastian isn't what he seems and Valentine comes with a warning to the Clave.Also Clary's past and family comes to light.
City of Glass excellently written; if you start reading it you will not want you to put it down. The genres have stepped up a notch from the last book as it should be since in this book has the final battle between Valentine and the Clave along with Downworlders come and brings to light the loves that have been questioned.