Mardi Gras has come to Galveston Texas and with it the excitement of a new event, the first-ever Mardi Gras Marathon. Gina Malloy, a young journalist, is very involved in the planning of the event. When she enlists the help of her aunt, Sister Catherine Malloy, she is delighted to discover that Sister Catherine's friend, Martin Iberson, is the agent of one of the big stars of marathon events, Billy Champion. Gina is eager to meet Martin Iberson and his family and perhaps get a chance to meet and interview Billy Champion. All goes well until evil shows its face, and two of the marathon runners are killed. With the help of their friend, police lieutenant Richard Tierney, the nun and her niece embark on the task of finding out who murdered the runners, and as things progress, they find their lives in danger as well. But from whom? And why? Things become even more somber as they realize that the culprit could be someone they know. Eventually, Sister Catherine deduces that to solve the murders she must understand the character of the killer, and she finally comes up with the shocking solution to the Mardi Gras murders.