It's vacation time for outdoorsy Chicago man Chet Ripley, along with his wife, Connie, and their two kids, Buck and Ben. But a serene weekend of fishing at a Wisconsin lakeside cabin gets crashed by Connie's obnoxious brother-in-law, Roman Craig, his wife, Kate, and the couple's two daughters. As the excursion wears on, the Ripleys find themselves at odds with the stuffy Craig family.

Chaos ensues when two former college friends, one a housewife and the other the editor of a hip women's magazine, decide to swap lifestyles between them.

Count Yorga continues to prey on the local community while living by a nearby orphanage. He also intends to take a new wife, while feeding his bevy of female vampires.

Sixties couples Michael and Donna and Paul and Erica become involved with the intense Count Yorga at a Los Angeles séance, the Count having latterly been involved with Erica's just-dead mother. After taking the Count home, Paul and Erica are waylayed, and next day a listless Erica is diagnosed by their doctor as having lost a lot of blood. When she is later found feasting on the family cat the doctor becomes convinced vampirism is at work, and that its focus is Count Yorga and his large isolated house.