The protagonist of the story is a police detective named Roy who has been entrusted with the case of the serial killer known as "The Mentalist", a dark figure who kills his victims without leaving any trace. His long history of crimes made him famous and, over time, he found followers ready to help him.
One of them, a Peter Thompson, was brutally killed by his own master.
Investigating the murders of the Mentalist, the police found Peter's diary, a very important subject for the investigation as inside were described all the crimes he had witnessed, but above all they found important news about one of the mentalist's many shelters.
Peter describes this place in such detail that Roy can track him down, and so begins the adventure that aims to capture the Mentalist and put an end to the terrible crimes of this fearsome murderer.