A masterpiece of the Spanish Golden Age.
It is foretold that Prince Sigismund will become a tyrant. Alarmed, his father, the king, imprisons him. When he is released for a day as an experiment he proves the omens only too right, and, as a result, is incarcerated once more. Sigismund persuades himself that all that has passed is a dream and emerges to rule wisely and justly.