At the May Day dancing at Glasgow Cross Gil Cunningham sees not only the woman who is going to be murdered but her murderer as well. Gil is a recently qualified lawyer whose family still expect him to enter the priesthood. When he finds the body of a young woman in the new building at Glasgow Cathedral he is asked to investigate & identifies the corpse as the runaway wife of cruel unpleasant nobleman John Semphill. With the help of Maistre Pierre the French master-mason Gil must ask questions & seek a murderer in the heart of the city.