In 1543, at the University of Salamanca, in Spain, Fray Antonio Román, an Augustinian monk who spreads humanist ideas, considered heretical, among his more inquisitive students, a clandestine group of four led by the brilliant novice Luis de León, mysteriously dies in unspeakable circumstances. In the present day, the historian Lara Cabanes is hired to find out if the monk was murdered, as is suspected and she is told, but the task will not be easy to achieve.