" Believer " is the (Episode 22) of the police procedural drama Criminal Minds , which originally aired on April 18, 2018. It serves as the first half of a major cliffhanger that concludes in the landmark 300th episode. Episode Summary
Watch a detailed reaction and breakdown of the episode's opening discovery and initial investigation steps: "Criminal Minds" Believer (TV Episode 2018) - IMDb
The BAU discovers a "mole" within their own ranks—an FBI agent who is actually a member of the cult.