We have a brief appearance from Luke, thoroughly pissed that Clary and Jace et al didn't share that there's a weapon of mass downworlder genocide, but hey this is Shadowhunters everyone keeps secrets for no apparent reason. Especially from people who may help.
Speaking off, we have Izzy keeping her yin fen addiction (remember she's addicted because Victor decided giving his Shadowhunters vampire-venom based addictive drugs is totally a good idea. Because this is Shadowhunters and everyone is terrible and has the intelligence of a slime mould) has now turned to vampires to get bitten from the source. Raphael steps in before she got herself killed (Why? Remind me again why Raphael cares about any Shadowhunter? Or do Downworlders just line up to try and save Shadowhunters from their own bad decisions? Is there like a council? "Fred, you need to go to Edinburgh, the Shadowhunters there have decded to jump off high places while yelling 'angel wings'. Try to stop them") and advises her to sweat it out, endure and defeat her addiction. He knows - because Magnus saved him (because Magnus exists to serve everyone. It's a rule). She ignores him and gets one bite from him - before returning and tempting him with her too powerful shadowhunter blood. This will not end well. Someone get Magnus on speed dial, he has another mess to fix.
We also have Simon finally telling Clary he loves her and Clary, remembering his very impressive 8 pack, decides she's totally good with this. They're in a relationship.
This episode brings us the return of Maryse Lightwood, the mother of Alec and Izzy, step-mother of Jace and general candidate for the Worst Person Ever.
She's a homophobe who hates downworlders so you can imagine what a great fan of Alec she is. She also was happy to stand by when the Clave decided to kill Jace. Because she's that awful. She's also passed on all her awful opinions to Max, Alec and Izzy's little brother. Since her husband/their dad Robert is still in Idris this means he can't be around for Max's coming-of-age new rune ceremony and traditionally he gets a party which Alec has to organise
And Alec decides the best way to do this and tell his mother to go fuck herself is to get Magnus to run it
Y'know, I'd love if a declaration that Alec truly loves Magnus didn't come more as a "fuck you mother" rebellion (especially sicne that rebellion is less "this is who I am you homophobe" and more "how dare you do this to Jace" which seems to reduce Alec turning to Magnus to be more about serving Jace - again- than about actually standing up for himself.) I'd also love it if his rebellion didn't involve Magnus serving. I mean, is anyone paying Magnus for the use of his house, the booze, the entertainment or anything else? Or is this just another chapter in the endless litany of freebies Magnus dishes out.
Let the most awkward party ever commence. Maryse is awful, Max is awful, Magnus is patient. And to make it all much much worse we have a paranoid/hallucination/insecurity spell cast on the whole party which has everyone snarling at each other. Jace thinks Maryse attacks him so knocks her out. Clary thinks Simon is cheating on her so needs Magnus to repeatedly tell her not to make a scene and make the event all about her. For once. And Clary drives Alec to jump off the roof (honestly I can understand the temptation if forced in Clary's presence for any length of time)
Magnus realises things are up an manages to break the paranoia spell.
The warlock - Iris Rouse who Clary owes - has had her child threatened by Valentine to force her to steal Magnus's spell book. We have a pretty awesome warlock fight which, of course, Magnus wins because he's chief warlock for a reason. He captures Iris who reveals she's given his book to Valentine which is probably a problem and would really help if everyone could focus on Valentine even briefly. Before she's whisked off to wherever, she invokes Clary's promise and demands that she find her daughter.
Well that just ruined the party.
This gives everyone chance to discuss Clary's specialness and the angel Ithuriel because Clary has realised they shouldn't keep this a secret. They were keeping it a secret because... Shadowhunters everyone keeps secrets. No reason, they just do. Clary's super special angel blood of specialness means she can use the sword to do the genocide thing - so Valentine will be hunting her. Again
She and Jace also got a vision from Ithuriel on how to destroy the sword with a special demon. And, yes, they were keeping this secret again. Whyyyyyy is everything a secret? Seriously why is vital information like this not shared with anyone but one clueless and one pouting teenager? Entire species are facing genocide, this is not the time to be secretive.
Time for the Maryse redemption. She says how sorry she is to Jace and makes it clear she considers him family. She doesn't apologise to Alec, of course, but she does cry on his shoulder because Robert is cheating on her. Yay, when your unrepentant homophobic parent decides to bond with you by leaning on you for comfort and support!