Master Surgeon, Flavio Gaglione, recently pardoned by Pope Clement V for poisoning Cardinal Fournier, returns to Spain to resume his life as a surgeon. In his quest to develop a new elixir, he applies his new medicine to a young nun at the convent of Mary Magdalene and to Constance, the daughter of King Peter the Cruel of Spain. In both cases he is successful. His patients recover fully, but Gaglione is tripped up by Cupid's arrow, as he falls madly in love with Sister Elizabeth (Adriana Munoz). Accused of having plotted with the devil to seduce Adriana he is arrested by the Inquisition, not just for the abduction of Adriana but for his repeated blasphemous conduct. Following a daring escape from being burned at the stake, Gaglione crosses into Aquitaine in service to the Black Prince. In a tale of scheming among the nobility, both Gaglione and Adriana are sacrificed to the Inquisitor of Burgos.
