A recently released psychiatric patient named Tom Sykes (Gary Busey) creates a home for himself in the attic of the Dreyer family’s newly built house. He uses electronic devices to spy on them. The Dreyer’s beloved dog Rudolph is murdered by Tom in an attempt to defend his family from the titular hider.

After that, Tom focuses his attention on the mom, Julie (Mimi Rogers), going so far as to watch her skinny dip in the pool. He interferes secretly in the relationship between Julie and her husband, Phil (Michael McKean), planting bogus evidence of secret love affairs. He befriends the Sykes’ son Neal (Kurt Christopher Kinder) and teaches him fighting techniques.

After two explosive arguments, Phil leaves the house and moves into a hotel. Seeing this as an opportunity, Sykes pretends to be a visitor who lives on Willmington St. a couple of blocks over. His attempt to insinuate himself into their lives works at first, although the weird neighbor Gene (Bruce Glover) is the only one who distrusts him…