Magnus invites Alec to a party full of Warlocks. The party is to welcome the new High Warlock of Brooklyn, Lorenzo Rey.
The earth starts shaking and all of the Warlocks' magic starts reacting uncontrollably.
Maia checks Simon's forehead and can't see the mark.
Jace invites Clary out for their first official date. He asks Izzy for help with choosing a location and planning a night Clary will never forget.
Lorenzo thinks Magnus is at fault for the corrupted magic at his party. Magnus knew the demon who had the power to mess with magic. Lorenzo threatens to banish Magnus from New York City.
Asmodeus, the demon powerful enough to mess with magic, is Magnus's father.
Maia is hassled by a wolf over her relationship with Simon; she threatens him to leave them alone. Jace calls Simon for restaurant suggestions.
Luke and Izzy team up to find out the point of possession for Tim.
Alec visits Lorenzo to get his statement about the magic at the party. He helps Magnus sneak into the mansion.
Clary and Jace head to the restaurant; Jace didn't realize he needed to make a reservation. The waitress leads them to a communal table where Maia and Simon are on a date. The four get drinks, but they have an awkward night, especially when it's revealed Maia and Jace slept together.
Magnus does a spell to check out the layline of the mansion. The vines are red and the power forces Magnus back. He warns Alec that the power comes from a very dangerous demon.
Four new possessed people kneel before Lilith inside the chapel. Lilith slices their neck to let the blood flow onto the alter.
Catarina's powers go haywire as the laylines are affected again. Luke and the Shadowhunters check in to make sure she's fine.
Jace reassures Clary that he wants to be with her. He doesn't want to take things too quickly with because he doesn't want to ruin it.
Alec wants to establish a line to the Institute so that Magnus can eliminate the demonic corruption. Raj argues against it because, if a corruption occurs, the Institute could be destroyed.
Raj locks Alec out of the system of the angel core and refuses to reverse the code. Izzy is unable to hack the code. Magnus's power reaches critical mass; Alec manually fixes the code and the charge cleanses the system.
Lilith stops the blast of energy before it hurts her. The alter is still protected.
Raj and his friends are banished to an island for work. Lorenzo takes credit for fixing the laylines.
Jace has another nightmare that he kills Clary.
Izzy finds video footage of Tim being infected by the demon. She and Jace have no clue which demon infected him.
The wolves try to evict Simon from the boatyard. One of them attempts to hit him with a bat, but his mark starts glowing and it create an energy barrier that pushes the wolf away.