When a headless body is found in a garden, and then a severed head is found in the same garden a short time later, people assume that one goes with the other. Father Brown isn't so sure.
A young man relates a story of premonition of danger which he calls "The Red Signal." That evening at a dinner party, the entertainment is a medium who, in a trance, warns, "Do not go home." Later, one of the people is murdered.
