With everything that Simon has gone through this past year, a family dinner for Yom Kippur – the Jewish Day of Atonement – poses as a real challenge. How can he come clean about being a vampire and especially about what just happened to his family? And if he is stressed out, what if he can't control his vampire urges? Looking to take care of this himself, Maia insists on helping him out whether he likes it or not. Meanwhile, Clary and Jace go on an unsanctioned mission and test out their newfound rune powers.
- Joan Gregson as Helen
- Benjamin Sutherland as Young Ithuriel
- Peter Binswanger — writer
- Paul Wesley — director
- "Four Walls (The Ballad of Perry Smith)" - Bastille
- "Anchor" - Novo Amor
- "Upstairs Room" - Paul Cook & The Chronicles
- Filming ended on March 29, 2017.
The following are elements adapted from The Mortal Instruments:
- Clary was able to create a Portal, a feat no other Shadowhunter is capable of.
- Portaling to Idris without sanction from the Clave will open the Portal around Lake Lyn, whose water has hallucinogenic properties. A person who drinks from the lake, if left untreated, can lose their mind.
- A Portal that breaks may sometimes leave shards of glass that may give glimpses of the last destination the Portal was used to reach.
- Maia has a dead brother who was their parents' favorite.