Basilius Valentius, a monk and medic from the monastery of Camaldoli, is called to Florence to treat a mysterious illness that
has befallen his old friend Lorenzo de Medici. Shortly after his arrival Lorenzo dies though, and as Basilius finds evidence
suggesting his old friend was murdered, he is determined to find the murderer. This, however, is not an easy endeavour, as
the powerful Roman dynasties of the 15th century are caught in a brutal struggle. During his investigations Basilius gets help
from various places: an old friend and the Borgia sons of whom he does not know much are helping him with his investigations
– but who can be trusted?