[jason taylor]

Why not do a generic one on secret societies? You could have mundane ones like the Mafia and other criminal groups, political groups, or full out Ancient Conspiracies. You can even have groups that are open about their existence and have no dishonest motives but conceal some of their membership and/or activities, or simply make a fetish out of internal symbology, etc (like a German dueling society, a Chinese surname society, for instance).