In the 13th Century, a sect of Christianity called Catharism arose in the south of France. Their beliefs were so at odds with Catholicism that the Pope ordered the Albigensian Crusade, the purpose of which was to exterminate the Cathars. The crusade lasted nearly twenty years, but when the Cathars made their last stand at the fortress of Montsegur, there was a rumor that some of the survivors escaped with the sect's fabulous treasures. Eight centuries later, Professor Zebulon Pike O'Dowd leads an expedition to find the treasures. But someone else is also after the Cathar treasure and that rivalry leads to a series of brutal serial killings that baffle the NYPD. Deputy Chief Inspector Mag Goldman of the Homicide Bureau turns to his friend Professor Bradley Davison, who had assisted the police many times in the past, to help solve the murders and ultimately unlock the secrets of the lost Cathar Treasure.