Conversation so far:
What was The Firefly?
The Firefly was the first operetta written by composer Rudolf Friml, with a libretto by Otto Harbach.
What was Rudolf Friml's first theatrical success?
After a month of work, Rudolf Friml produced the score for The Firefly which became his first theatrical success.

Question: What was it about?
Self-contained rewrite: What was Rudolf Friml's operetta, The Firefly, about?