Courage is a small, spotted dog who spends his life on pins and needles, terrified and suspicious of anything out of the ordinary. When supernatural forces rear their hideous heads, however, Courage sheds his nervous demeanor and exhibits enough fearless ingenuity to protect the ones he loves.

Eustace enjoys simple pleasures. He likes reading his newspaper, watching television with his wife, Muriel, and terrorizing his dog with a big, scary mask. Despite Courage's frantic efforts to protect, Eustace dismisses his dog's frenzied antics with two simple words: "Stupid Dog!"

To Courage, Muriel is both his reason for living and the source of his paranoia. Muriel provides Courage with a warm lap and a refuge from the scare tactics of Eustace. Courage, meanwhile, protects Muriel from the continuous succession of bizarre creatures that descend upon their farmhouse.