Aaron Hotchner (Thomas Gibson) and the entire team will do their best to flush out the mole in the Behavioral Analysis Unit (BAU) when "Criminal Minds" returns for its eleventh season.

Master Herald reports that the premiere episode of the police procedural series will center on the squad's discovery of a traitor in their midst and the subsequent investigation to reveal who it is. A mole is in disguise among the BAU members and has been leaking all the information about ongoing investigations. If that person will not be apprehended soon, the team stands to lose a lot as there will be no hope in apprehending criminals.

The investigation will reportedly be one of the biggest revelations in the upcoming installment of the CBS series. It will coincide with BAU's mission to track down a villain who has a curious way of treating his victims. In the "The Dirty Dozen," showrunner Erica Messer told TV Line that the case would require the help of the entire team, including Hotchner, Dave Rossi (Joe Mantegna), Derek Morgan (Shemar Moore), Spencer Reid (Matthew Gray Gubler) and Penelope Garcia (Kirsten Vangsness).

This murderer first injects his victims with something and once they are incapacitated, he will paint their faces before killing them. According to Messer, this particular modus operandi was the culprit's way of expressing his insecurity about his appearance.

"This UnSub does some, obviously, weird stuff to his victims, which includes painting their faces. And then we learn why he's doing it, because he himself has a really hard-to-look-at face," Messer said.

Meanwhile, fans can expect to see a variety of guest stars in the new season, including Tim Kang of "The Mentalist" and Marisol Nichols of "Teen Wolf." According to Cartermatt, both actors will be featured in an episode titled "The Witness," which is slated to air on Oct. 7. Nichols will play an FBI agent who helps the BAU in preventing a vast attack on Los Angeles, while Kang will play a medical supply worker.

"Criminal Minds" will return for its eleventh season on Wednesday, Sept. 30, at 9 p.m. EST on CBS.