Marjery Louise Allingham is an English "Golden Age" detective writer, held in the same circle as Agatha Christie, Dorothy Sayers, and Ngaio Marsh. According to Christie herself, among her colleagues, Allingham stood out “like a burning lamp.”
Campion receives an anonymous letter in which an angel, Peters, and a mole are mentioned in a cryptic way. That very morning, The Times reports the death of R. I. Peters. It seems that the deceased is none other than his former schoolmate, nicknamed Pig—a man Campion couldn’t stand since his school days and about whom he had heard nothing for more than twenty years. At the funeral, he meets another former classmate who has received exactly the same letter, and speaks with Peters’ doctor, who is certain that the cause of death was pneumonia. But at the coffin something strange happens: behind Campion a painfully familiar cough rings out—just as the vile Pig used to cough…