Prostitutes are being murdered within the boundaries of Father Mike's inner city parish in Chicago. Father Mike is an amateur sleuth along the lines of Chesterton's Father Brown. He has helped detectives solve a number of murders. Now he sets out to work on trying to find the killer or killers of the prostitutes. In the meantime he persuades Gloria Winthrop, a very successful and wealthy lawyer, to set up a half way house to get the prostitutes off the street. He enlists the help of a young priest, Jim Norwood, in his endeavor. His efforts to solve these murders lead him into the highways and byways of the ever-expanding mystery, the dark night of crime and heavy heartbreak. His dogged persistence causes him to clash with the local detectives and his own Cardinal who frowns on his avocation as a crime solver. He does succeed in befriending Detective Lulu Larson who aids him in his efforts to reclaim the prostitutes from their way of life.