Robert Knepper stars as cult leader Billy Grimm on the hit TV show "Cult," and Alona Tal is the former cult member-turned cop out to get him. Their show, "Cult," is the show-within-a-show on The CW's new, identically named thriller, "Cult," which starts Tuesday. Got that? (Liane Hentscher/The CW Network photo)

"Cult" focuses on a journalist (Matt Davis) investigating the possible link between his brother's disappearance and the rabid fans of the fake show. He gets help from a researcher on the show (Jessica Lucas). (Jack Rowand/The CW Network photo)