'Criminal Minds' Season 9 Episode 21 Spoilers: College Frat Investigated After Party Goes Terribly Wrong [Video]

CBS will air an all-new episode of "Criminal Minds" Wednesday in which a college fraternity will come under investigation by the FBI's Behavioral Analysis Unit (BAU) after a wild and crazy frat party appears to go very wrong.

In a video promo for the upcoming episode, "What Happens in Mecklinburg," a frat is seen having a party involving lots of booze and pig masks. However, things take a turn for the worst when someone wearing a pig mask approaches three people who are chained up like slaughtered pigs in a desert dungeon. The episode will also give more insight into what's going on with Morgan.

According to CarterMatt, the official synopsis for Episode 21 reads: "A series of targeted kidnappings near Memphis have the BAU searching for a commonality between the missing persons and a motive to lead to the UnSub. Meanwhile, Savannah vents her frustration to Morgan about the amount of traveling he does for his job."

A number of guest stars will make an appearance in the episode, including Colleen Donovan as Christy White, Elly Schaefer as Lauryn-Anne Harrison, Alisha Wainwright as Debbie Martin, and Marshall Teague as Dr. Edward Calder, reports Movie News Guide.

Later on in the season, "The Office" alum Brian Baumgartner will guest star on the CBS sitcom as a serial killer. TVLine reports that Baumgartner will play a man who ends up at an unexpected crossroads in his life and then goes on a killing spree in Episode 22, "Fatal."

"Criminal Minds" S9E21, "What Happens in Mecklinburg," will air on Wednesday, April 9 at 9 p.m. EDT on CBS.

Watch the promo video below.