When two mischievous teens Libby (Andi Garrett) and Kit (Sara Lane) are home alone with Libby's younger sister Tess (Sharyl Locke), they amuse themselves by prank call asking prank questions, telling whomever answers: "I saw what you did, and I know who you are." Libby places a call to Steve Marak (John Ireland (actor)), a man who has recently murdered his wife, Judith (Joyce Meadows) and disposed of her body in the woods. Believing he has been found out, he decides to track down the caller to silence her.