"I know exactly what’s going to happen," she said of the new series, which will take place in Los Angeles five years after the conclusion of the "TMI" books. "I’m still wrapping up the last book in the ‘Mortal Instruments’ series and the characters of ‘The Dark Artifices’ are introduced in it."

You’ll meet the newbies when “City of Heavenly Fire” hits stores in early 2014 (ugh, yes, that’s still so far away). But even Cassie’s learning more and more about them as she continues to work on the book. "I’m really getting to meet them for the first time in 'The Mortal Instruments.' They come in and we get to see them and their interactions with each other,” she said. “I really feel like in the book it’s an act of Clary and Jace and the other characters passing the torch on to this next generation younger than them and being like, ‘Now the adventure is your adventure.’”

But you can still see some of your favorite "TMI" characters when they cross over to "TDA"--that is, if they don’t bite it by the end of the series. “The surviving ones [will cross over],” Clare teased. “If you live through ‘The Mortal Instruments,’ you will probably be in ‘The Dark Artifices.’”

Whoa, ominous! "Ominosity is my middle name,” Cassie joked, with the caveat that things won’t get completely crazy. “It’s not like ‘Hamlet.’ It’s not like we end with the wind blowing over the corpses, but there’s some deaths.”

Unfortunately said deaths could hit pretty hard. “I hope so,” Cassie said. “Otherwise you don’t feel it.”