Jace is feeling down about activating the Soul Sword. He and Alec practice sword-fighting to take his mind off it. Alec urges him to tell Clary the truth about his feelings.
Simon is worried about his new ability. He's not sure why he's able to walk out into the sun as a vampire. Jace interrupts his date; Simon promises to never reveal Jace's secret of having pure angel blood.
Valentine is being tortured by the Clave. They want to find out where he's hiding the Mortal Cup.
The Clave Inquisitor demands that Jace and Clary fall in line or they'll be reprimanded like Aldertree. Aldertree is being held in Idris.
A mysterious demon is searching for the Mortal Cup as well. After Valentine's cronies don't give up the location, he uses magic to suffocate and kill everyone in the bar.
Izzy is going through withdrawals from the vampire blood. Alec is looking after her and keeping it a secret.
A faction of the werewolf pack is upset with Luke after the deaths from the Mortal Sword. They bring up the idea of turning humans into werewolves. One of the members challenges Luke as Alpha, but he backs down.
Izzy cracks and goes to visit Raphael. She begs him to give her some vampire blood so that she can slowly get off the addiction. Her withdrawal turns ugly and she leaves after nearly stabbing him.
The demon ambushes Izzy in the alley and demands the Mortal Cup. They fight and after he kills innocent bystanders, a blonde Shadowhunter named Sebastian arrives to break it up.
Simon confides in Maia that he can now stand in the sun. She's happy for him, but she warns him to not show it off.
Magnus confirms that Azazel is the deman who is killing people. Raphael is also at Magnus's apartment and confirms that Izzy tried to get blood from him.
The group go searching for Izzy and resort to interrogating Valentine. They need the Cup from him. Valentine reveals the truth about Jace to Clary.
The mysterious blonde Shadowhunter who saved Izzy is from the London Institute. He gives Izzy a liquid that will speed up her addiction withdrawal. He urges her to not leave hiding until she's in much better health.
The disgruntled wolves abandon Luke's pack to start their own group in Philadelphia. Luke plans to recruit from other packs to save his group.
Simon reveals that he's going back to NYU for music. Raphael surprises and confronts him about being a 'Daylighter'. Simon refuses to explain how he became one.
The group uses Mangus's help to summon Azazel. The demon uses his ability to subdue the others, but before he's able to kill Valentine, Jace uses his ability to break free and stop the demon.
Izzy calls to update Alec. She isn't coming home for a while until she's clean and cured. Sebastian is strangely burning himself on the stove fire.
The banishing spell didn't work properly and now Azazel is trapped inside Magnus's body.