Madzie appears at the Institute and uses her magic to steal the oxygen. The Shadowhunters in her path suffocate. Valentine takes control of the Institute and threatens Clary to return or he will kill Simon.
Dot reveals that if Jace touches the Soul Sword, the weapon will be destroyed. Magnus looks into their minds to view this vision and confirms this meaning. Though, if Jace touches the sword, he will die.
Raphael reveals his feelings to Isabelle. He spots Alec's warning messages to Isabelle on her phone, but keeps it a secret. He goes to explore.
Alec and Victor Aldertree team up to fight their way inside the Institute.
Simon tries to convince Valentine to stop and be the father Clary needs. Valentine video calls Clary and slices Simon's throat in front of her. She has a half hour to give Simon blood or he becomes dust.
Maia blocks Luke's car and starts a fight with him and Jace. Luke subdues her and they place her in the car with them.
Magnus and Clary head to the location to meet Valentine, but Raphael and the vampires arrive to stop them. He is about to bite Clary until Luke, Maia and Jace arrive to stop him.
Aldertree shares with Alec the story about his fallen love Eva. Eva was a werewolf.
Clary enters the Institute to save Simon. She offers her blood to him and he feeds. As Valentine's minions pulls Simon from her, the shield is dropped and the glamor is revealed to be Jace in disguise.
The Downworlders are teaming up to storm the Institute and destroy the Soul Sword. The pack isn't too thrilled with Luke.
Magnus calms Madzie down and earns her trust. He wants to help her.
Simon and Jace subdue Valentine and his minions. They make a run for it from the room to find the sword.
Aldertree isn't able to bypass the security codes. As Valentine's minions arrive to stop him and Alec, Isabelle arrives to fight them. She defeats all four fighters.
Valentine is about to force Clary to pickup the sword until Simon stops him. He saves her in time. Jace picks up the Soul Sword, but it isn't destroyed. The blade is empowered. Valentine used it to cause pain to a group of Downworlders charging into the Institute.
All of the Downworlders affected are dead. Activating the sword means that Jace has pure angel blood inside him. Alec frantically goes searching for Magnus.
Jace and Valentine begin fighting. Valentine reveals that the venom he infected Jace as a baby was angel blood, not demon blood. He also reveals that he is not Jace's father and Jace is not related to Clary or Jocelyn.
Clary applies a rune to the Soul Sword. While she stops Jace from killing Valentine, the sword goes missing.
Alec finds Magnus outside the Institute and admits that he loves him. Magnus says he loves Alec too.
The sun appears and Simon isn't burned from the sunlight.
Isabelle and Raphael reunite, but she tells him to leave her alone forever.
Jace is going to tell Clary the truth, but he walks in on her kissing Simon. Simon has brought Clary outside to show her that he can be out in the sunlight.
A mysterious, hooded figure has stolen the Soul Sword.