The film takes place at the University of Prague in 1820, where a poor young man named Balduin is the city's wildest student and greatest swordsman. He becomes smitten with Countess Margit Schwarzenberg after rescuing her from drowning but knows he cannot pursue his love for her because he is poor. A sorcerer named Scapinelli offers Balduin 100,000 pieces of gold in exchange for any item to be found in the student's room. Balduin agrees, thinking he owns nothing, but is astonished when Scapinelli calls forth Balduin's reflection from the mirror and absconds with it. Balduin attempts to woo Countess Margit but is haunted by the appearance of his mirror double. Baron Waldis-Schwarzenberg, cousin to the countess and a rival suitor, challenges Balduin to a duel for her hand. Privately, the countess' father begs Balduin not to kill the Baron, as he is the last surviving heir to their family fortune. Balduin agrees but is thwarted when his double appears at the duel in his place. Balduin sneaks into Margit’s room and she confesses her true feelings to him. However, she is frightened by the appearance of the double, collapsing in a swoon. Dejected, Balduin returns to his room to retrieve a pistol. He fires at his double, only to drop dead himself. Scapinelli then comes into the room takes the contract Balduin signed with him tears it up, throws it like confetti and disappears out the door.