People Under The Stairs(1991)
A boy wants to help his sick mother make rent before eviction, so he goes into the house of the wealthiest family in the town. he gets locked in and discovers a CRAZY family lives there. the parents who are actually brother & sister have a girl locked in the house as well as lots of other boys in the basement who weren't "good enough" to be their children. thus... PEOPLE UNDER THE STAIRS ... it is a good but strange movie.. the boy saves the girl, the town and the people under the stairs!!
This trailer was originally posted to YouTube by trenq13.