Knowing that psychiatrist Haggis has suggested her commitment, psychotic Diana is inspired by professional golfer Jerry's "sudden death" playoff against rival Mike. Seducing Jerry at the country club, Diana suggests a murder pact, according to which she will kill his opponent and he will slay her psychiatrist. Assuming that she is joking, the drunken Jerry agrees. As they make love Diana's concealed camera and tape recorder document the act. After stealing Jerry's club and lighter Diana locates Mike on the course, runs the golfer over with a cart, and clubs him to death. Diana now demands that Jerry fulfill his part of the bargain, threatening to incriminate him in Mike's murder if he refuses. As Jerry consults his estranged wife, Lee, Diana phones the couple and plays the tape. Following Jerry's departure, Diana attempts to run over Lee with a beach buggy. Fearing that Jerry has complied with Diana's demand, Lee rushes to Haggis' office, where she finds her husband conferring with the physician. Her plot discovered, Diana is arrested.