Investigative drama series "Criminal Minds" might have brought back Derek Morgan (Shemar Moore) on its fifth episode of the show's 13^th run, but the next episode will surely be mind-boggling and puzzling.

The next installment will see a number of women going missing in Virginia, a puzzle which the BAU must answer by deciphering what these women have in common. This is according to the synopsis for the sixth episode of season 4 of "Criminal Minds." The episode, titled "The Bunker," will be directed by Aisha Tyler, who plays Dr. Tara Lewis.

The title itself gives viewers an inkling of what the next episode is going to be about. Fans might see the Behavioral Analysis Unit (BAU) baffled as to how a number of women have gone missing. It would not be a giveaway for the bureau, as they need to figure out how the women are connected.

Aside from this, the next episode will probably be a puzzle needed to be solved in order to find the women, who are likely trapped in a bunker, as per the title. This might probably eventually lead to a bigger problem. BAU will then have to act fast in order to locate these women; otherwise, they might end up with a bunker full of corpses instead.

Derek Morgan's (Shemar Moore) return had been setting the flame burning, as he tried to comfort Penelope Garcia (Kirsten Vangsness) of a past stressor, for episode 5, titled "Lucky Strikes." "I wanted to take your place. It's okay, I got you," Morgan said as he comforted Garcia. To the fans delight, Morgan's appearance had indeed helped Garcia.

Moore left the show in March this year, after 11 seasons. His character had to shift his attention to his family, requiring him to leave BAU. Moore's new project, "S.W.A.T" is set to premiere on Nov. 2, Thursday, on CBS.

"Criminal Minds" season 13 episode 6 will air on Nov. 1, Wednesday, at 10 p.m. EDT on CBS.