A teenage girl who was molested by her father calls David Kelley, a radio psychologist working for KDRX, and shoots herself on the air. Later, a real estate broker shows off a house to prospective buyers, and discovers the decomposing remains of another realtor in the washroom, the fourth victim of a psychopath dubbed the "Open House Killer". Outside Grant Real Estate, which David's girlfriend Lisa runs, someone digs through the trash, and takes discarded Seller Listings. The vagabond goes to one of the listed houses, and murders the realtor and buyer inside with a plunger that has had razor blades attached to it. The Open House Killer then calls David at KDRX, and opines that his victims deserved their fates. After an open house, Harry breaks into the property, and electrocutes the realtor with frayed wires. As Harry continues to make rambling calls to KDRX, a detective named Arnold Shapiro is assigned to work with the station to try and track Harry down. In an attempt to protect their employees, the real estate agencies institute new safety precautions, though these do little to deter Harry, who murders another agent by hanging her. Barney Resnick, Lisa's unscrupulous business rival, visits a prospective client, a dominatrix who agrees to sell her home through his agency if he has kinky sex with her. Harry follows Resnick, decapitates him with an axe, and snaps the neck of the home owner. The next day, Harry abducts Lisa, who gives cryptic hints about her whereabouts when Harry calls KDRX to taunt David. David tracks Lisa and Harry to an empty house, and as the authorities swarm the building, Harry expresses disappointment over the media not being present, and rants about how corporations and the real estate industry drove him to kill, as they made it so he could never have a place he could call his own Just as Harry is about to slit Lisa's throat, he is shot and knocked through a glass door by Detective Shapiro. Despite the severity of his injuries, Harry still tries attacking, and is finally killed when Shapiro knocks him off a balcony.
Moria gave Open House a zero, and stated that while it was more ambitious than most other slashers of the time and had an intriguing antagonist, it was still "a very poor film" that was dully directed, flatly photographed, and failed to generate any real suspense. Hysteia Lives! found the film "unrelentingly tedious" and gave it a one out of five, writing "Despite a few cheesy flourishes, Open House is a snoozer of the first order".
