Even as fans of 'Criminal Minds' have been waiting for the suspense thriller to return for Season 11 on the small screen, CBS has just released a trailer of the premiere episode that reveals some vital plot details. Apart from introducing the new BAU member Dr. Tara Lewis, portrayed by Aisha Tyler, the clip shows that there is a mole in the team, which is working to solve a bizarre case.

IB Times reports that the first promo of 'Criminal Minds' Season 11 teases Hotch and shows the BAU team working on a very critical and bizarre case that involves them handling a criminal, who overpowers his victim without a sound and then injects them.

This is consistent with what 'Criminal Minds' show runner Erica Messer hinted at during an interview with TVLine. She had said, "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."

In fact, CBS had also hinted earlier that BAU will be trailing a serial killer who has left evidence behind, indicating that it is someone who is determined to take revenge.

Aside from this, in the video clip one can clearly hear Hotch saying that someone tipped off the killer and there is a mole in the BAU team. Now, it remains to be seen who that could be.

While fans know the BAU team very well to be suspecting anyone, there is a great possibility that the new team member, forensic psychologist Dr Tara Lewis, could turn out to be the mole. However, this seems to be a very obvious prediction that if it is not anyone from the old members, it has to be the newbie.

Apparently, the show runners will not give it away that easily. Furthermore, fans are aware that one more BAU team member will leave the show. Hence, it is very likely possible that could also be the mole who will be asked to leave.

The promo trailer also introduces the newly-appointed psychologist Dr Tara Lewis, who is filling in for Jennifer Jareau (AJ Cook). In the promotional video clip, Lewis, who is assisting the BAU team solve the case, is seen elucidating her reasons for joining BAU.

'Criminal Minds' Season 11 premieres on CBS at 9:00 pm on Sept. 30.