Jonathan transports the penthouse to Paris. Clary makes a case to Jonathan about letting her leave the penthouse with him.
Simon and Isabelle go underneath the city in search of the oldest vampire. Isabelle reveals that she's "repulsed" by rodents.
Magnus makes Alec breakfast in bed. They begin their first training in weaponery and hand-to-hand combat. Magnus reveals his years of training; the intense fighting drives them to makeout and hookup.
Jace checks up on Luke's tip and believes him about the penthouse moving.
Simon finds the oldest vampire alive. He is revealed to be Cain and he has his own mark.
Jonathan agrees to take Clary into Paris. He refuses to her use his stele to do the disguise. Jonathan performs the spell for her.
Cain reveals that Lilith manipulated him into killing Abel. Lilith used her demonic magic to turn him into a daylighter; the Seelie Queen gave him the mark. Cain tells Simon that the Seelie Queen is the only one who can remove the mark; he gives him the rock he used to kill Abel to help with making a case.
Magnus is rushing into making the most of his time since he now is mortal.
Jace and Luke teleport to Siberia in search of Clary; they don't find the penthouse, but they discover her footprints and strands of hair.
Jonathan takes Clary to a cafe in Paris; he explains that it was the first place he visited after escaping Edom. He met Sebastian in the cafe and kidnapped him. Jonathan wants to be good after witnessing all the happiness at the New York Institute.
Alec tells Magnus to stop rushing; he needs to savor the moment. Jace pulls them into the search for Clary; the group will search for places around the world that could support the penthouse.
Clary steals a stele from a Shadowhunter in Paris.
Meliorn leads Isabelle and Simon to the Seelie Queen; he invites them both to hookup later. The Seelie Queen agrees to remove the mark, but it will be a tough ask that will push Simon to the limit.
Jonathan tries to make a deal with a demon shopkeeper to get the Morgenstern Sword. The demon already sold it; he refuses to tell Jonathan to whom he sold it. Jonathan kills the demon.
The French shadowhunter takes Clary away before she's able to send a message back home. Jonathan snaps his neck after she begs the shadowhunter for help.
Simon does the ritual to remove the mark from his forehead. He needs the blood of a mortal or a Nephilim to restore his health; Isabelle gives him her blood. She lets him bite her.
Luke, Alec, and Jace find Clary in Paris. She stabs herself in the leg so that Jonathan will flee. Clary and Jace kiss.
Jonathan transports the penthouse to a new location.