After defeating Valentine Clary starts packing for her trip to Idris, the Shadowhunter home country. Jace doesn‘t want Clary to go because he dreads the thought of something happening to her. Jace decides to ask Simon to try and persuade her into not going but it doesn‘t work. While they are in Idris Valentine shows up declaring war against the Clave. Valentine has all the Mortal Instruments now. How will he use them? And against what?