Nightbreed, released in 1990, was the big-screen treatment of Cabal, a short story by Clive Barker, who is best known for the Hellraiser series. The story starts off in what would be deemed reality by the viewer, as we meet our protagonist, Aaron Boone. He dreams of a town called Midian "where the monsters live." Disturbed by his dreams, his girlfriend insists he seek help. His psychiatrist convinces him he's a psychotic killer and hands him a bottle of what he tells Boone is lithium, when in reality the bottle contains LSD. The psychiatrist tells Aaron he has 24 hours to turn himself in and sends him off with the LSD/"lithium." Boone gets hit by a truck while wandering, hallucinating, and ends up meeting a character in the hospital who tells him how to get to Midian. What Boone finds is a city under a graveyard that thrives in the darkness of their underground world. Every horror and erotic impulse one can imagine is represented in the inhabitants of Midian.
At first Boone is not allowed admittance to Midian as only "monsters" - people who have committed unspeakable sins - are allowed to enter. Boone tells them he has killed many women and deserves to be there, but they can smell innocence on him, and they try to drive him away. Boone is attacked and bitten by one of the Breed. He escapes and is shot down and killed by local police, but in the morgue he comes back to life due to the bite he received and returns to Midian, where they are forced to accept him into the fold.
The movie turns into an allegory for the fight of good against evil from this point onwards. The Breed are discovered by the locals and must fight back and defend what is theirs in order to just survive. Which side is good and which is evil blurs and the viewer must decide which is the morally just side.