Dame Lettie Colston is the first of her circle to receive these anonymous calls, and she does not wish to be reminded. Nor do her friends and family - though they are constantly looking out for signs of decline in others, and change their wills on a weekly basis.
As the caller's activities become more widespread, soon a witch-hunt is in full cry, exposing past and present duplicities, self-deception, and blackmail. Nobody is above suspicion. Only a few, blessed with a sense of humour and the gift of faith, can guess at the caller's identity.