For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Many years prior to the Da Vinci Code movie the Opus Dei was already known to be a secret society by the Spaniards. They are big in that country, they control most of the private medical facilities. They are exactly like the Freemasons, they look to be great citizens, do great social deeds, have hospitals, especially for children but they have demonic rituals and degrees they must rise to. A former Spanish Catholic nun once gave me a book that is not allowed to be printed not distributed in Spain about the Opus Dei, and that's the only way that I know of to truly understand them. She was able to smuggle it out. It's very hard to know the truth about them, but they are NOT what they seem on the surface.