A delegation of the Inquisition, headed by Rainerio Sacconi, an infamous inquisitor, is travelling to a remote monastery in Languedoc. Accompanying this delegation on behalf of the Templar Order are Christian de St Armand, a Templar Preceptor Andre and their Jewish friend Eisik.
On the very night of their arrival a monk is murdered. Thereafter monks are found dead, murdered in heinous ways, with clues being left in Andre's room pointing to the next victim.
Andre and Christian, a medieval Sherlock Holmes and Dr Watson, must solve the clues. Racing in and out of scriptoriums, churches and underground tunnels they must find the killer before the inquisitor can burn innocent men and unwittingly stumble on the secrets of the monastery.
Will they stop the murderers and prevent the inquisitor from getting his hands on the monastery's secrets?