"Black Museum" has one of the more tenuous plots in this season of Black Mirror, but it redeems itself with a solid lead.
Letitia Wright, who stars in the much-anticipated Black Panther movie, plays a young black woman named Nish who "stumbles" upon a black museum in the middle of nowhere. While waiting for her car to charge, she chats with the skeezy owner of the museum, Rolo Haynes. The collector of criminal oddities tells her about all the sketchy things he has done in the past, including involvements with corrupt brain experiments.
Eventually, we learn that Nish isn't a harmless passerby — she's the daughter of an incarcerated man whose consciousness Haynes has exploited for personal gain. Haynes has been inviting tourists to simulate her father's execution repeatedly, to the point where he has lost most of his mental capacity. To avenge her father, Nish punishes Haynes.
It's exciting to see a female lead who exists outside of a conventional moral spectrum. Nish is not quite good, but she's not quite bad. She takes morality into her own hands outside of a legal system that has wronged her father, much like how Frank Castle destroys criminals as the Punisher.