In Victorian London, a wealthy and deeply bored Prince Florizel, accompanied by his loyal companion Colonel Geraldine, roams the city incognito seeking unusual diversions to break the monotony of his existence. Their search leads them to a desperate young man who reveals the existence of a clandestine organization known as the Suicide Club.

The club operates out of a secret underground apartment where members who have grown weary of life gather to gamble with death. The rules are chillingly simple: each week, a deck of cards is dealt among the members. The person who draws the ace of spades becomes that week's designated victim, while the one who draws the ace of clubs must act as their executioner, making the death appear as an accident. The entire operation is overseen by a mysterious figure known only as the President.

What begins as a macabre amusement for the prince and his friend turns deadly serious when a club member is actually killed. The charade ends, but Prince Florizel, bound by the club's articles of membership which he signed to gain entry, cannot involve the police and must settle the matter himself as a man of honor. The situation becomes personal when the prince himself draws the fatal card and is marked for death, only to be rescued at the last moment by Colonel Geraldine.

Escaping his own demise, Prince Florizel forces a bargain with the club's President, who must accompany the colonel's son to Paris with the understanding that one of them will die. In Paris, the President employs a beautiful female accomplice who lures young Geraldine to his doom. The young man is shot and his body is returned to the prince hidden in a trunk. Horrified by the tragic outcome, Florizel abandons any remaining restraint and returns to the club to confront its nefarious leader directly. The final confrontation takes the form of a duel, during which the President's accomplice briefly turns out the lights, but the President himself receives the fatal blow, allowing the prince to finally escape the club's sinister grip.