With two of the three Mortal Instruments missing, everyone is on the hunt for the last one — The Mortal Mirror. Jace and Clary are on the hunt to recover it first before it falls into enemy hands. But along the way, Clary realizes that her brother Jonathan may be closer than she thought. Meanwhile, Isabelle has a hard time accepting the fact that her little brother Max is growing up, and Maia struggles to bring her guard down with Simon.