Jonathan panics after being uncovered. He urges Valentine to run, but he refuses. Clary, Jace and Isabelle charge into Jonathan's apartment; they find the real Sebastian's dead body being possessed by a demon. They vanquish it.
The group confide to the Inquisitor that the Mortal Mirror is Lake Lynn.
Magnus warns Luke and Raphael of the Seelie Queen's upcoming arrival. The Queen offers asylum to all the Downworlders to enter her realm if Valentine's wish of killing the Downworlders is accomplished.
The Seelie Queen serves as the voice of the Downworlders in their discussions with the Shadowhunters. Alec and team need their help to stop Valentine, but the Queen rejects their plans. She believes the Downworlders should protect themselves.
Luke and Raphael are remorseful about the decision, but they stand behind it. Raphael hopes things had worked out differently with Isabelle.
Maia gives Luke's orders to the pack to be on the lookout for Valentine and Jonathan. Russell is apprehensive at first, but agrees.
Maia and Simon make their relationship exclusive. Clary bursts in and ruins the moment. She needs Simon's help to convince the Seelie Queen otherwise.
Valentine discovers the true identity of the Mortal Mirror. He tries using a warlock to escape, but the warlocks have placed wards to keep Shadowhunters in the city (if anyone crosses the line, they'll die). The werewolves arrive to stop them.
Simon seeks a meeting with the Seelie Queen and she arrives in her adult form. She offers whatever he wants, if only he joins her court. He declines.
Clary comes up with an idea to create a rune that will trigger the connection between herself, Jace and Jonathan. She applies the rune on Jace's chest and their runes start glowing. They feel a connection with each other.
Jonathan warns Valentine of his glowing runes. He fears that his father plans to abandon him, but Valentine discourages this. He applies a Shadowhunter rune to an innocent man; the rune will drive him to insanity.
Clary, Alec, Isabelle and Jace enter a mausoleum to find the "Forsaken", innocents imbued with the runes. They fight the creatures to discover that Jonathan has taken Jace captive.
Jace and Jonathan fight. Jonathan stabs Jace and before he's able to deliver the final blow, Isabelle arrives to stop him. She distracts him enough for Jace to stab Jonathan through the back. Jonathan dies and his body is thrown in the river.
Jace and Clary kiss.
Maia is missing; her smashed phone was found outside the restaurant. She's been transported to the Seelie realm.
The Seelie Queen and Valentine meet; he whispers her something that she desires. The two for for a walk.