The third installment of Dorothy L. Sayers's famous Harriet Vane mysteries, unfolds at the all female Shrewsbury College at Oxford. Upon returning to Oxford for the first time in years for a school reunion, Harriet Vane is asked by her old professors to turn her talents as a detective writer to practical use. Someone is terrorizing the faculty and students of the college by sending vicious anonymous letters, eventually leading to the destruction of collegiate property and the attack of faculty members. Harriet struggles with the realization that the perpetrator may be a professor as well as the realization of her growing feelings for Lord Peter Wimsey.