We're promised a chill up our spine with this broadcast... An honest-to-goodness chill that you haven't felt since you were a kid reading spook stories. This is a mystery that is one of the strangest ever told. Psychologists and people who study the dark ways of the mind will know it's true. The rest of us must just marvel. The most important man in our story, is of course, the detective Robert LeGroux, the world-famous detective of the French police force, who called this the perfect crime.