Harriet Vane is a mysterious and notorious author who stood trial for murder and was freed thanks to famous detective Lord Peter Wimsey. When Harriet returns to her alma mater, to attend the Gaudy dinner, her short stay is marred by the discovery of a sheet of paper with an offensive drawing, and a poison pen message. She learns from the Dean of the college that there has been an outbreak of vandalism and anonymous letters, and she accepts to investigate confidentially. As Harriet wrestles with the case, trying to narrow down the list of suspects who might be responsible for poison-pen messages, obscene graffiti, wanton vandalism including the destruction of a set of scholarly proofs, and the crafting of vile effigies, she is forced to examine her ambivalent feelings about Wimsey, who declared his feeling for her after the trial. The attacks build to a crisis. There is an attempt to drive a vulnerable student to suicide and a physical assault on Harriet that almost kills her. Wimsey eventually arrives to help, and she gains a new perspective on the case and on him also.