Bonanza - Season 1 Episode 21
The Spanish Grant

In "The Spanish Grant", a young bargirl, Rosita Morales is pretending to be a Spanish noblewoman named Isabella Marie Inez de la Cuesta and at the end of the story, its revealed she is really Rosita Morales, but on the other hand, is she really Rosita Morales? This little twist at the end is simply entertaining everytime its viewed, with the viewer able to determine the young womans real identity at the end of act four.