If you like horror, then write horror screenplays. The main and most crucial element of horror is isolation. From a story telling standpoint, isolation forces the characters to confront the villain with limited resources in a confined area where they can’t escape. From a production standpoint, isolation means there’s a minimal amount of set locations needed, which means horror films are among the cheapest to produce. As a result, horror screenplays are cheap to make and popular so they’re easy to make and sell as well.
Besides making horror films cheap to produce, isolation also enhances the horror because the main characters can’t escape. “Alien” was a science fiction horror film that trapped the crew on a starship. “10 Cloverfield Lane” traps the hero in an underground shelter. “Green Room” traps a band in a seedy nightclub. “Night of the Living Dead” traps the main characters in a house surrounded by zombies.
One reason why isolation works so well is because it keeps the main characters from getting help. It doesn’t matter how scary a hockey mask, chainsaw wielding maniac might be if you can call in the local SWAT team to gun him down with machine guns and hand grenades.
One notable exception to the need for isolation is “It Follows.” In this movie, the horror comes not from isolation but from the unpredictable appearance of the villain and its relentless pursuit of the hero. No matter where the hero goes, the villain will follow her. Even worse, nobody else can see this villain but her. So even though she’s free to roam all over the place, she can’t get anyone to help her.
Any time you have a horror story, think of isolation first. Even though the hero in “It Follows” can freely roam around, she’s isolated because nobody else can see the villain stalking her and she can’t kill the villain with conventional weapons, so it doesn’t matter if she gets a bazooka or an atom bomb. She can’t stop the villain who keeps relentlessly stalking her. it may not be physical isolation, but it is emotional and psychological isolation, which is far scarier and enhances the horror.
If you’re going to write a horror screenplay, isolate your main characters. It’s easier to physically isolate them like in most horror movies where the heroes are stuck in a camp on an island or trapped in a house that’s isolated by a blizzard. As “It Follows” shows, isolation doesn’t always have to be physical but emotional. Keep your hero alone and helpless and that’s the real root cause of creating horror.