'Criminal Minds' season 12 episode 10 spoilers: BAU deals with girls who kill for leisure; 'Lost' vet to join series

From one serial killing to another, the Behavioral Analysis Unit's (BAU) new case in the next episode of "Criminal Minds" season 12 brings them to upscale neighborhoods in San Diego.

The promo for the episode, "Seek and Destroy," sees a group of young ladies who "just wanna have fun." And by fun, they mean kill neighbors.

Prentiss (Paget Brewster) realizes in the "Criminal Minds" season 12, episode 10 promo that these killers are "young and innocent-looking" making them difficult to catch.

BAU newcomer Stephen Walker (Damon Gupton) also warns the team that these girls won't stop, making them ever more dangerous with such combination.

"Criminal Minds" season 12, episode 10 will mark the third episode Gupton appears in. His character was officially welcomed to BAU in the episode "Scarecrow" from last year.

From the looks of it, the team will have a lot on their hands in "Criminal Minds" season 12, episode 10. After all, the attacks often lead to deaths. But it appears that Walker will be of great help here.

In other news, "Lost" alum Harold Perrineau will be brought this season for a major recurring role. He will play the role of Calvin Shaw, whose alliance is still a bit murky.

According to the official character description picked up by TVLine, Perrineau's character is "a former FBI agent incarcerated for killing one of his informants. Shaw has a run-in with a BAU agent and the team must determine whether he's a friend or foe."

Perrineau is one of the many additions to "Criminal Minds" season 12 in the show's effort to reel from the exit of Shemar Moore and the firing of Thomas Gibson.

There is no word yet on which episode Perrineau will debut. Either way, it is looking to be one exciting storyline. More details about this should be revealed soon.

"Criminal Minds" season 12, episode 10, "Seek and Destroy," airs Wednesday, Jan. 11, at 9 p.m. ET on CBS.