A young opera dancer tries to help her mother financially by performing in a dubious cabaret.

For the Marquis Barbezieux de Saint-Rosay, nobility is important. If anything can comfort her, it's her family tree. In order to erase any doubt he invites in his castle a cousin of his established in Scotland, whom he instructs to bring him his titles of nobility. A first person introduces himself, calling himself his cousin, but it's not him. Then one, then two, then three false cousins ​​appear in turn. Will the real Saint-Rosay of Scotland eventually present itself?