Don Carlos, the Crown Prince, is passionately in love with Elizabeth, the French princess to whom he was once betrothed. Carlos's tyrannical father, King Phillip II of Spain, decides to marry Elizabeth himself. The young prince's hatred for his cold, distant parent knows no bounds. He enlists old friend Rodgrigo, the Marquis of Posa to act as a go between. But Posa decides to convert Carlos's and Elizabeth's youthful passion into a full scale rebellion against the king' bloody regime.

Interweaving themes of honour, family and the corruptive nature of power in the times of the Spanish Inquisition, Don Carlos demonstrates a frustrated and near incestuous passion, sexual jealousy and intrigue, finally leading to rebellion and murder.