'Criminal Minds' season 12 episode 15 spoilers, news: BAU works on case where victims are burned by acid; Reid forced to rely on Shaw

Rossi (Joe Mantegna) and his team will be busy working on a case where the victims are scarred by acid attacks. Meanwhile, Reid (Matthew Gray Gubler) will have no choice but to trust Calvin Shaw (Harold Perrineau) inside the prison.

On the next episode of "Criminal Minds" season 12, titled "Alpha Male," the featured unsub is an attacker whose chosen weapon is acid and who inflicts scarring damages on its victims.

"The BAU investigates when several young men and women are victims of disfiguring acid attacks. Also, Dr. Reid begins to settle into his new surroundings," the episode's listing on The Futon Critic reads.

While Rossi and the team are busy with this case, Reid will have to adjust to the environment inside the prison. As seen from the episode 15 promo, Reid will be surrounded by other prisoners, but one man will appear to give him a hand.

"You gotta learn how to survive," Shaw says as he urges Reid to trust him.

Given Shaw's past of having a fellow agent incarcerated, Reid handing over his trust will be a big risk. However, the criminal specialist will have no choice but to trust him since prison is a hostile environment for a guy who put several criminals behind those bars.

Meanwhile, Reid still has no memory of what happened in Mexico. According to executive producer Erica Messer, Mr. Scratch might be behind Reid's unfortunate predicament.

"We're certainly pursuing that path. That's the most logical person to be involved in this, especially given our history just this season with Scratch. He will be a big player in the back nine," Messer shared with TV Guide.

If Mr. Scratch is behind it all, fans would have to wait for episode 21 of "Criminal Minds" season 12 to confirm it. Messer said that Reid's arc will end in episode 21 and 22 in a two-part finale.

"Criminal Minds" season 12 airs every Wednesday night at 9 p.m. EST on CBS.