In the middle of the night at the Museum of Volterra, young archeologist Fabrizio Castellani is immersed in his work-research into the famous Etruscan statue known as ''the shade of twilight''. Completely engrossed, he is startled by the phone ringing. An icy female voice warns him to abandon his work at once. A series of gruesome killings shortly follow, throwing the people of Volterra into a panic. The victims - all involved in the desecration of an unexplored tomb - have been torn to pieces by a beast of unimaginable size. Fabrizio is in charge of excavating this Etruscan tomb.
Fabrizio is joined in his fearless investigation of the past by Francesca Dionisi, a vivacious young researcher, and foremost by Lieutenant Reggiani, a brilliant carabinieri officer assigned to the case. Fabrizio is convinced that a single event has set off the entire chain of events. What is hiding inside the enigmatic statue? What lies behind the bloodthirsty rage that has lain in wait for all these centuries? What tragedy is hidden behind the inscription? Will Fabrizio manage to unravel these secrets without being sucked into the spiral of violence himself?