Fidelio

Ludwig van Beethoven: Fidelio

Wer du auch bist, ich werde dich retten!

(Whoever you are, I will save you)
- Leonore

Leonore disguises as a man to save her husband who is - unjustly - held a (political) prisoner.
She therefore calls herself Fidelio, meaning "faithful, true" and sneaks into the prison as a new servant to Rocco, who has the charge over the prison.
As the drama devlops, Leonore is growing so much over herself, that she is able to forget her original plans and is risking everything to save a stranger whom Rocco has order to kill. Wer du auch bist, ich werde dich retten!
As Fidelio and Rocco are in the unknown prisoner's vault, she discovers with terror that it is Florestan, her long-missed husband. Yet she cannot reveal herself until the moment Don Pizarro comes to kill Florestan. She throws herself in-between: Töt' erst sein Weib! (You must kill his wife, first!)
All comes to a good end with the arrival of the Governor, a friend of Florestan's - even Don Pizarro is not dealt with like other opera-villains, he is given over to justice, not to death.

Beethoven shows strong morals in this opera: fidelity, freedom, justice, devotion...to name only a few. I would call Fidelio a sum-up of what I believe Beethoven believed.