Carol, a woman who hates insects, is unhappily married to Steve, an amateur entomologist. She secretly loves Steve's business partner, Larry, and would like to make their affair a permanent arrangement. One day while shopping, she encounters a gypsy who sells her something that will help her achieve her goal without leaving any traces. However, when Janet carries out her plan, she begins to be terrorized by a Death's Head moth, and discovers that things are seldom as simple as they seem, and that every action has its consequences.

The series was retitled "Circle of Fear" beginning with this episode and no longer utilized the opening and closing segments featuring Sebastian Cabot as the host.