Someone very dangerous will cause Booth (David Boreanaz) and Brennan (Emily Deschanel) a lot of sleepless nights in the second half of season 11 of the long running FOX series "Bones."

Executive producer Michael Peterson told Entertainment Weekly that in episode 13, a new serial killer would be introduced. This madman has reportedly killed before, during the time the couple took their hiatus from the Jeffersonian. When he decides to take a new victim again, things will become so bad even Brennan and Booth question whether they are to be blamed for not being there to apprehend him the first time.

The showrunner also admitted that this killer would be a recurring character. It appears that the specialists would not be able to capture him so easily, as he would be seen until the season finale. The revelation would reportedly be "a major, cliffhanger kind of twist." Peterson also hinted that Brennan and Booth have never faced such a scary antagonist, a monster of all monsters among all criminals they have put behind bars.

"It's a very twisted serial killer that we're dealing with: somebody who really is truly unhinged. It's the closest to a horror kind of episode that we've ever done. Don't watch it alone. Make sure to bring a blanket and somebody else and maybe a large baseball bat to protect yourself," the EP said.

Meanwhile, fans will be sad to know that FOX is thinking of ending the long-running series' run in season 11. Co-chairman and CEO Dana Walden reportedly said that they have yet to talk about the renewal prospects of the show. She was quick to assure, however, that if "Bones" would not be picked up for season 12, creator Hart Hanson and Co. "will be given plenty of time to start writing a meaningful ending to the show."

When asked whether it would possible to continue the series without its lead stars Boreanaz and Deschanel, Walden immediately dismissed the idea. According to TV Line, the two actors are currently on a legal dispute with FOX over the show's profit.

Bones" season 11 is expected to return in spring, but FOX has yet to announce a specific return date.