A show within a show, “Cult” (8 p.m., CW) isn’t so much a network drama as the idea for a drama, or maybe the marketing scheme for a drama. But given the slim pickings on the CW and other networks, that may be enough.

”Cult” begins with grainy documentary footage of alleged cult leader Billy Grimm (Robert Knepper) surrounded by willowy, brainwashed blondes. A minute later, the film stock changes and we see one of those blondes, now older, in search of a victim of Grimm’s cult. Soon the action dissolves, the cameras pull back and we’re shown the set for the hit CW show “Cult.”

At this point, “Cult” establishes itself as a kaleidoscope of refracted narratives. And it gets even more confusing. One of the show’s fans, Nate (James Pizzinato), is convinced that Grimm’s cult is real and that its followers are after him. He shares this with his older brother Jeff (Matt Davis), a once-promising journalist with problems of his own. At first, Jeff dismisses Nate’s fantasies as just another immature obsession, but when Nate vanishes, leaving behind a bloody trail of evidence, Jeff springs into action and invades the “Cult” set. There he meets fetching production assistant Skye (Jessica Lucas), who shares the opinion that there’s something creepy and potentially dangerous about the show’s too-passionate fan base.

Give “Cult” credit for its tremendously clever concept and consistently creepy atmosphere. The show is all but guaranteed to be remembered for the cryptic tagline, “These things just snap right off,” uttered by all of Grimm’s brainwashed victims right before they die. That’s something you might blurt out tomorrow around the water cooler. If you dare.

Tonight’s other highlights:

• The art of the sandwich reconsidered on “The Taste” (7 p.m., ABC).

• Sutton doubts her mother on “The Lying Game” (8 p.m., ABC Family).

• Savino contends with a wild clientele on “Vegas” (9 p.m., CBS).

• Julia and Tom welcome a fresh voice on “Smash” (9 p.m., NBC).

• Megan returns to work as “Body of Proof” (9 p.m., ABC) returns from the network deep freeze.

• Raylan feels trapped on “Justified” (9 p.m., FX).