With Luke in dire need of help, Jace, Clary and Simon take him to Magnus' lair in hopes of saving his life. Once there, the story of how Valentine came to be evil, and Jocelyn and Luke's past is revealed to Clary in hopes of triggering her memory of what happened to The Mortal Cup.

Meanwhile, Isabelle and Alec are tasked to restore their family name in the eyes of The Clave.

With word of Alec, Jace and Isabelle’s “extracurricular activities” with Clary reaching The Clave, a convoy is sent to observe the Lightwoods running the New York Institute. Once The Clave representative arrives, it is very clear how much trouble the Lightwoods are in.

Meanwhile, Clary is faced with a devastating decision.

Tasked with arranging his brother Max’s Rune Ceremony, Alex decides this would be the perfect opportunity for his family to get to know Magnus. But with tensions flying among the different Shadowhunters, Max’s big event quickly becomes an evening where they all must face their biggest fears. Meanwhile, Simon makes a bold move as Isabelle finds an unlikely new ally.