Season 6's Black Mirror episode titled "Demon 79."
The episode is considered as perplexing and demands close attention to comprehend.
"Demon 79" is presented as a film set in the Black Mirror universe.
It takes place in the 1970s and has a different timeline and concluding than the other episodes.
There are Easter eggs and references to earlier Black Mirror episodes in this episode.
Nida's violent dreams come true when she meets Gaap, a demon.
Nida's ideas of a dismal future might be affected by a self-help book she reads.
The true explanation is that Nida's encounters with Gaap were supernatural rather than imagined.
The police inquiry into the death of the first victim confirms Gaap's findings.
Charlie Brooker: Television Writer and Black Mirror”