It can always get worse. If you thought the Carter's stunning death was this season's rock bottom, think again. EP Jonah Nolan ominously warns: "As taxing, difficult and ultimately lethal as the battle [with HR] was, that was just the beginning of the challenges put in front of our heroes," he tells TVLine.com. One of those challenges involves not one or two, but a "clusterf--k of villains" targeting our dogooding team. "Person Of Interest" returns on Jan. 7 on CBS at 10/9c.