Poindexter "Fool" Williams is a resident of a Los Angeles ghetto. He and his family are being evicted from their apartment by their landlords, the Robesons. The Robesons, who are believed to be a married couple, call themselves Mommy and Daddy. They have a daughter named Alice.
Leroy, his associate Spencer, and Fool break into the Robeson's household by using Spencer to pose as a municipal worker. The Robesons leave the home shortly but Spencer doesn't return. Fool and Leroy break into the house to look for Spencer, and they find his dead body and a large group of strange, pale children in a locked pen in a dungeon-like basement.
The Robesons return and Fool flees while Leroy is shot to death by Daddy. Fool runs into another section of the house, where he meets Alice. She tells him that the people under the stairs were children who broke the "see/hear/speak no evil" rules of the Robeson household. The children have degenerated into cannibalism to survive and Alice has avoided this fate by obeying the rules without question. A boy named Roach whose tongue was removed also evades the Robesons by hiding in the walls.
Fool is discovered by Daddy and is thrown to the cannibalistic children to die. However, Roach helps Fool escape, but is critically wounded. As he dies, he gives Fool a small bag of gold coins and a written plea to save Alice. Fool reunites with Alice and the two escape into the passageways between the walls. Daddy releases his dog Prince into the walls to kill them. Fool tricks Daddy into stabbing Prince and he and Alice reach the attic where they find an open window above a pond. Unfortunately, Alice is too afraid to jump and Fool is forced to go without her. He promises to return for Alice.
Fool finds out the gold he has is enough to pay his rent and for his mother's surgery. He also finds out that Mommy and Daddy are a brother and sister coming from a long line of crazy inbred family members. They started out as a family that ran a funeral home selling cheap coffins for expensive prices, then they got into real estate. After they made a lot of money, the family got greedy, and the greedier they got the crazier they got. Fool vows to help right the wrong. He reports the Robesons to child welfare and as the police are investigating the house, Fool sneaks back in and reveals to Alice that she is not their daughter; she was stolen from her birth parents, as were all the other children in the basement.
Mommy finds out that Alice knows the truth and believes that Fool has turned her against them, so she attempts to kill Alice. However, the cannibal children charge at Mommy causing her to flee and run into a knife held by Alice. The children then seize her and throw her into the basement, where she lands at Daddy's feet. Daddy finds Fool at the vault, where Fool sets off explosives, which demolishes the house and causes the money to blow up through the crematorium chimney and into the crowd of people outside. Daddy is killed in the explosion and Alice and Fool reunite in the basement. Meanwhile, the people outside claim the money distributed by the blast, and the freed children venture into the night.Brandon Adams as Poindexter "Fool" Williams
Everett McGill as Man / "Daddy" / Eldon Robeson
Wendy Robie as Woman / "Mommy" / Mrs. Robeson
A. J. Langer as Alice Robeson
Ving Rhames as Leroy
Bill Cobbs as Grandpa Booker
Kelly Jo Minter as Ruby
Sean Whalen as Roach
Jeremy Roberts as Spencer
John Hostetter as Veteran Cop
The film opened at the #1 spot at the box office, taking in over $5.5 million that weekend, and stayed in the top 10 for a month until early December. The film went on to gross over $24,204,154 domestically (U.S.) and $7,143,000 internationally, bringing its worldwide total to $31,347,154.
The People Under the Stairs has received mixed to positive response from critics. It currently holds a 61% 'fresh' rating on movie review aggregator website Rotten Tomatoes based on 22 reviews. Austin Chronicle wrote, "this is the work of the Wes Craven we came to admire".
In his review for The New York Times, Vincent Canby described The People Under The Stairs as "an affirmative-action horror film," containing "its share of blood and gore," and lauded the film for being "mostly creepy and, considering the bizarre circumstances, surprisingly funny" in that "it's impossible not to like fiends who, having just dispatched someone in an especially nasty way, can't contain their natural high spirits. They dance."
Craven at one point said he would like to remake the film along with The Last House on the Left and Shocker. However, after the release of the 2009 remake of The Last House on the Left, news of a remake fell dormant until 2015, when it was announced (shortly before Craven's death) that the director was developing a People Under the Stairs TV series for the SyFy Channel.
Universal Studios Florida incorporated some of the film's plot as well as the house into a haunted house several times for their annual Halloween Horror Nights event. It is also featured on the drive-in movie screen in the Twister...Ride It Out attraction.