All horror stories, fictitious or true, are tragedies.
All tragedies are with suffering.
All suffering is from the Three Poisons (of greed, hatred and delusion).
To have unhappy endings, there must be no resolution.
To have no resolution, there must be no transformation of the poisons.
To have no transformation, there must be no Dharma practice.
Much greed might spill to the afterlife as hungry ghosts.
Much hatred might spill to the afterlife as vengeful demons.
Much delusion might spill to the afterlife as wandering spirits.
Such greed might clash with the also greedy alive.
Such hatred might clash with also hateful alive.
Such delusion might clash with also delusional alive.
To have happy endings, there must be resolution.
To have resolution, there must be transformation of the poisons.
To have transformation, there must be Dharma practice.
All good horror stories, fictitious or true, are good lessons (or cautionary tales).
All good lessons are with ending of suffering.
All ending of suffering is from the Three Poisons ended.