Enrico Rosatti is a former privateer who plays the violin in a Florentine tavern, trying to drink away the memory of his broken heart. It seems Rosatti has sunk so low that he is irredeemable, but Captain Palashov, the envoy of a powerful Russian prince, sees Rosatti as an opportunity for his own redemption. Having failed to persuade the famous violin virtuoso Count Morelli to come to Russia, Palshov offers Rosatti a place at the court of Catherine the Great, provided he can pose as Morelli. Rosatti warms to the courtly life and falls in love with Maria, an adventurous courtesan who, like him, is of less than noble lineage. Unfortunately, in his colorful former life Rosatti had made some enemies, and a vengeful Polish mercenary named Jan Magnuski threatens to destroy the credibility of the new Morelli.