At the beginning of 1964, the music world experiences something completely unexpected. Maria Callas returns to the opera stage as the prima donna. Her "Tosca" at the Royal Opera House becomes a sensation. Maria Callas wants to show everyone once again that she deserves the title of "prima donna assoluta." On the condition that star director Franco Zeffirelli take over the direction, the exceptional singer agrees to sing the role of Tosca. The BBC recorded the 2nd act of the opera for television. It is one of the most dramatic acts in opera history: in order to free the painter Cavaradossi from the hands of torturers, Tosca ends up murdering the police chief Scarpia. The film footage is one of the rare opportunities to see Maria Callas in an opera performance and to experience her highly emotional performance art and vocal abilities.