There's only one thing on Clary's mind, and that's finding her mother. Jace seems to feel Clary's intensity. I'm sure there's some sort of plan forming in his mind.
Izzy seems like the type of girl to admire a good weapon. Looks like she has lots to choose from, but that middle one has captured her attention. Maybe because it's big and shiny? Clary doesn't seem to be paying attention, but she should. She needs a few tips.
Jace realizes that Clary's memories are the key to finding the Mortal Cup on Shadowhunters. "The Descent Into Hell is Easy" is the second episode of the show's first season