Secret clubs (synonyms: hidden dens, criminal lairs; example mythonyms: the Underclub) are a worldbuilding location where the criminal element can conduct business. They may be gambling dens, brothels, nightclubs, drug dens, or more. They are often at a secret location usually requiring special knowledge or a password to enter. They are home to addicts, thugs, gangsters, mob bosses, and more. Some may be cult lairs.

When designing a secret club, consider first it’s location. They are often found in unusual or hard to find places. They may be located in the slums, docks, or the back alleys. The doorway may be guarded or hidden. Once inside there may be multiple rooms, usually a larger space for customers and then a series of backrooms for other ‘business’. There may be secondary secret entrances or exits.

Also consider the typical clientele of this establishment. Secret clubs may be high class and cater to socialites, the well connected, and the rich, or they may be seedy locations that serve and take advantage of the dregs of your fictional society.

Who owns and who runs your secret club?