The film was followed by the sequel Sometimes They Come Back... For More.
Psychologist Jon Porter learns that his mother has just mysteriously fallen to her death. Jon and his teenage daughter Michelle return to Jon's hometown of Glenrock for his mother's funeral. Once there, painful memories return. Thirty years earlier, when Jon was a child, he witnessed the brutal murder of his older sister Lisa, who was stabbed to death in a cave by a thug named Tony Reno and his two friends Vinnie and Sean. But Jon managed to throw an electrical wire into a puddle of bloody water they were standing in, killing all three of them.
Michelle becomes friends with mentally retarded gardener Steve, as well as two girls, boy-crazy Maria, and Maria's psychic best friend, Jules, who used to clean her grandmother's house. The night after the funeral, they invite Michelle to go to the dinner with them, saying they would like to get to know her before she goes home for her 18th birthday. At the dinner, the girls are greeted by a boy who looks a lot like Tony Reno, even with the same name. While Maria develops a crush on him, he seems to be attracted to Michelle. He gives Michelle an old wristwatch as an early birthday present, then leaves. Maria and Jules are then murdered.
Meanwhile, Jon is pestered by Father Archer Roberts, a priest he came to when Lisa was murdered. He tells Jon his mother's death was not an accident.