Diana (Carol Lynley) is the wealthy, mentally unbalanced woman who seduces the local golf pro Jerry (Paul Burke). She proposes they each do the other a favor by eliminating their rivals. The drunken golfer laughs and agrees to kill Diane's psychiatrist Dr. Haggis (Whit Bissell), believing Diane is kidding. She is dead serious and kills the golfer's main competitor Mike (Philip Carey) by running him over with a golf cart. Diane tape records their conversation and uses it to blackmail the golfer into going through with his end of the bargain. Jerry goes to Dr. Haggis with the problem while police Lieutenant Gavin (Stephen McNally) is called in to solve the murder of the rival golfer.