A successful businessman (Seymour Cassel) has been left alone at home on a rainy weekend for his 40th birthday when his wife is called out of town on a family emergency.
When 2 soaked-to-the-skin girls, Agatha and Donna (Sondra Locke and Colleen Camp) show up at his door, he plays Good Samaritan and allows them in out of the rain so they can call a friend to pick them up. MISTAKE!!
Finding out he is all alone on his birthday, they temp him into the bathtub with them. The intimacy advances from there. It's a middle-aged man's dream turned into a nightmare!
He is soon held prisoner in his own house, and the girls reveal they are both underage (Uh-oh, they certainly don't look it) and act like they are escapees from a mental institution (which they are). They tie the guy up, trash the house, and even kill a delivery boy, all to the soundtrack song of children singing "Dear Old Dad". Very humbling.
They have a bizarre "countdown" to his death, which he now fully believes the two insane girls will carry out. They don't kill him but leave him a nervous wreck and go trapsying down the street like a couple of young trick-or-treaters. The surprise ending is too fitting to believe... being run over by a speeding SPCA van. (They had thrown the family cat through a window.)