The Ulmans are the central antagonists of The House of the Devil.


After her landlady gives her an extension on the deposit for her new apartment, college student Samantha Hughes takes on a babysitting job for Mr. Ulman  and his wife. Ulman asks to meet her but stands her up, later apologizing and offering to pay double the original salary. Samantha accepts and gets a ride to the remote mansion from her best friend, Megan, who expresses her distrust. At the house, Mr. Ulman pulls her aside and reveals that he does not have any children; the babysitting job is to attend to his ailing mother. Samantha balks but finally agrees, if he will pay her $400, a significant increase in her pay. Megan immediately leaves, citing Ulman's lies and peculiar behavior, but she promises to pick up Samantha later. Samantha stays, after accepting the money. On the way home, Megan stops in her car to smoke a cigarette. When her car lighter will not work, a stranger suddenly appears out of nowhere, startling her, and lights her cigarette for her. When Megan reveals that she is not the babysitter hired by the Ulmans, she is abruptly shot and murdered by the stranger.

After ordering a pizza, Samantha finds evidence in the house that Ulman has likely murdered the original mansion owners and stolen their car. She panics and dials 911 but eventually manages to calm herself down. However, drugs in the pizza cause Samantha to pass out. When she comes to, she finds that she has been bound and gagged. As a lunar eclipse darkens the night sky, the Ulmans carry out a horrific and bloody ritual, with Samantha at the center. She escapes halfway through the ritual, but horrific images begin appearing in her mind. She stabs and kills most of the cultists, which includes the stranger that had killed Megan, but Ulman chases her out of the house and through a nearby cemetery. There, he tells her she was chosen. Samantha threatens him with the gun used to kill Megan, but Ulman passively accepts his fate, claiming to be a messenger and gloating that she's too late. Instead of shooting him, she shoots herself in the head, to Ulman's horror. The scene cuts to a broadcast about the strange lunar eclipse the night before, which has confounded scientists due to its abnormal length, as Samantha is revealed to be in a hospital bed, in bandages. A nurse walks in and reassures the unconscious Samantha that "You will be just fine. Both of you".