Favraux, an unscrupulous banker, receives a threatening note, signed by "Judex", demanding that he pay back the people he has swindled. He refuses, and apparently dies after a midnight toast at his masked ball. However, he is only drugged by Judex and locked away. Judex spares his life when the banker's widowed daughter, Jacqueline, rejects the inheritance. Meanwhile Diana Monti, the former governess, kidnaps Jacqueline to try to get the banker's money. But Judex is hot on her trail.