After Dr. Bill Harford's wife, Alice, admits to having sexual fantasies about a man she met, Bill becomes obsessed with having a sexual encounter. He discovers an underground sexual group and attends one of their meetings -- and quickly discovers that he is in over his head.

Harvard symbologist Robert Langdon is recruited by the Vatican to investigate the apparent return of the Illuminati – a secret, underground organization – after four cardinals are kidnapped on the night of the papal conclave.