The water fairy Rusalka falls in love with an earthly prince. In vain, Father Aquarius warns her. Her sincere feelings are met with human treachery...

Miller’s daughter Zuzanka Vojířová, betrothed to Ondřej Zachar, hesitates before marriage when Lord Peter Vok of Rožmberk invites her to his castle. There she bears his son Petříček, but his wife hides the child. After Vok’s death in battle, Zuzanka is expelled and lives as a beggar, reunited with her son and former fiancé, finding solace in the continuation of the Rožmberk lineage.