Prince Peter Karagin, an officer in the Cossack army, sees and hears lovely Lydia Marakova in the cafe Balalaika in St. Petersburg and wants to meet her. When he hears she likes to fraternize with a lower class of people, he gives a student 50 rubles for his clothing. She eventually accepts his persistant presence and they fall in love. Peter uses his influence to get Lydia an audition at the opera house, where she is hired and is scheduled to perform later. The Prince, however, is not aware that she, her father and brother are part of a revolutionary movement. Their mutual deception is quickly shattered when Peter and the Cossacks violently break up a revolutionary rally in the public square, where Lydia's brother is killed. Soon afterwards, she learns that the rebels plan to assassinate Peter and his uncle, General Karagin, at the opera house on opening night, and still in love, she warns Peter not to go to the performance.