Wedding plans are continuing at the Institute.
Jace is ornery. He doesn't care about the wedding and just wants to stay on mission finding a way to break Jocelyn's spell.
Clary and Alec talk and work things out. Alec gets a call from Magnus. Magnus tries to convince him to follow his feelings, but Alec blows him off.
Clary invites Simon to be her date for the wedding.
Clary, Jace, and Magnus have a meeting with Hodge to figure out which warlock was the one who gave Jocelyn the spell. Magnus figures out it was Ragnor Fell.
Izzy tells her brother he doesn't have to go through with the wedding. When he says he is, she tells him she's going to throw him a bachelor party.
Magnus, Clary, and Jace are in London field to find Ragnor. They come across wards where only the pure of heart and intention can cross. Clary gets inside, but not Jace or Magnus.
Clary finds Ragnor hiding in a painting. She tells him she'll give him anything he wants if he finds her friends. That's all he needed to hear and Magnus and Jace show up. He tells them they have to find the Book of the White. A Shax demon attacks and kills Ragnor before he can rummage through his stuff to find the location of the book.
Jace and Clary return to the Institute, while Magnus takes care of the dead Ragnor.
Jace thinks Lydia is a mole and Clary talks to her. She denies it.
Izzy visits Simon and asks about what makes a good bachelor party.
Magnus and Ragnor talk about Camille and how Camille killed Magnus and made him put walls up around his heart. He tells him if he finds someone to not let him/her get away.
Izzy brings Alec to his bachelor party. Jace shows up and the two talk.
It's wedding day. All the guests arrive. Lydia walks down the aisle and they are about to exchange rune rings when Magnus shows up. Alec explains the situation to Lydia who understands. The great Malec moment arrives and Alec leaves the altar and kisses Magnus.
Maryse is pissed.
Magnus takes the team to another room and shows them all the things he took from Ragnor's place. They find a bookmark when is the clue to finding the Book of White. It is Camille's bookmark and they will have to visit her in her prison in the basement of Hotel Dumort.
Lydia is getting her things to leave the Institute. She opens a secret compartment in the wall where she hid the Mortal Cup and is hit from behind.
Clary gives Jace the box her mother kept of things from her son.
Maryse confronts Alec.
Hodge goes to Jocelyn and puts on a hologram ring. Valentine shows up. Hodge is going to bring Valentine the Cup.