The movie Hider in the House is a psychological thriller that was released in 1989. The story revolves around a man named Phil (played by Gary Busey), who has become obsessed with a family that has just moved into a new house. He sneaks into the attic of the home and begins to spy on the family, watching their every move and becoming increasingly delusional.
As time goes on, Phil's obsession with the family deepens and he starts to take more drastic actions to ensure that he can remain hidden in the house. He begins to tamper with the family's belongings, hide secret messages around the house, and even tries to sabotage their relationships with one another.
As the family begins to suspect that something is amiss in their home, they hire a private investigator to try and get to the bottom of the strange occurrences. However, Phil outwits the investigator and manages to stay hidden in the house, growing more and more unhinged as he continues to obsess over the family.
The tension builds to a dramatic climax as Phil's true intentions are revealed and the family is forced to confront their worst fears. The film is a chilling exploration of the dangers of obsession and the lengths that some people will go to in order to preserve their illusions of control.