He also tells Tessa that the drug is killing him, but when Tessa asks him why he does not simply give up his dangerous profession, he declares that "there are more things to life than not dying". The following day, most of the Shadowhunters leave to kill de Quincy in his hideaway in Chelsea. Mortmain, the mundane who informed the Shadowhunters of de Quincey, comes back to the Institute to tell Will and Jem about the Dark sister who is trying to help the Magister with his army and her location.