A 1977 horror film directed by Creator/MichaelWinner, adapted from the novel of the same name by Jeffrey Konvitz (who also produced the film and wrote its screenplay adaptation with Winner). It stars Christina Raines and Chris Sarandon, with a supporting cast that includes Martin Balsam, Creator/JohnCarradine, Jose Ferrer, Creator/AvaGardner, Creator/BurgessMeredith, and Creator/EliWallach.

Supermodel Alison Parker (Raines) moves into a nice Brooklyn Heights apartment, and finds out the tenant on the top floor of her building is a blind priest, Father Hallerin (Carradine). Pretty soon, she starts having strange physical problems, trouble sleeping, and flashbacks to her attempted suicide.

Not to be confused with the [[Series/TheSentinel 1990s TV show]], or the 2006 movie starring Creator/MichaelDouglas and Creator/KieferSutherland.

!!This movie contains examples of:

* BigBad: [[spoiler: Charles Chazen, heavily implied to be {{Satan}} himself.]]
* BrokenBird: Alison has issues due to her father being abusive, which caused her to lose her faith and attempt suicide.
* CatScare
* ChristianityIsCatholic: The Catholic Church is responsible for [[spoiler: preventing the door to Hell from being opened.]] Alison is also a non-practicing Catholic at the beginning.
* DeadAllAlong: [[spoiler: The other residents of Alison's apartment building. Used to great effect when Alison talks with Michael at the end.]]
* [[spoiler: DownerEnding: Alison, much to her own dismay, becomes the next sentinel and now watches over the gate, as the brownstone is torn down and made into a modern apartment complex, with she ''still'' guards]].
* EvilAllAlong: [[spoiler: Michael, who had his wife murdered so that he could be with Alison.]]
* EyeScream: While fighting off the corpse of [[spoiler: her dead father]], Alison cuts his eye with a knife.
* FanDisservice: A flashback shows a young Alison walking in on a threesome her elderly father is having with two obese women.
* HornyDevils
* HotAsHell: The apartment is a ''gateway'' to Hell
* LegionsOfHell: "I am one of the Legion of the Dead."
* PeekABooCorpse: [[spoiler: Alison's undead father.]]
* ReligionIsMagic / ReligiousHorror: The film plays with this, enforcing the usage of ChristianityIsCatholic along with the fact Catholic priests keep the gate closed.
* ThoseTwoGuys: Detectives Gatz and Rizzo.
* YouCantFightFate: [[spoiler: Alison ends up becoming the next sentinel, despite trying to escape this fate.]]