A fake count seduces and blackmails rich women on the Riviera.

Count Sergius Karamzin, an adventurer, and his two cousins, Olga and Vera, lease a villa at Monte Carlo and cultivate the friendship of American envoy Andrew J. Hughes and his wife, Helen, who is flattered by the flirtations of the count. While strolling in the country, the count and Helen take refuge from a storm in a hut, and though they are obliged to remain overnight the arrival of an old monk keeps the count from revealing his intentions. At the casino the diplomat's wife wins, and when the party retires to the count's villa for poker, Mrs. Hughes, in response to a secret note from the count, meets him in the tower, where he wheedles her out of her money and begins to seduce her. Meanwhile, Hughes, having discovered the cousins cheating at the casino, returns to the hotel. The count's maid, a victim of his lechery, becomes desperately jealous, sets fire to the villa, and leaps into the sea. The count and Mrs. Hughes are saved by jumping into a life net, and Hughes, becoming aware of the count's intrigue, attacks him and arranges a duel for the following morning. Infuriated by his folly, the "Princesses" drive the count from the villa; at the house of Ventucci, for whom he has been passing counterfeit money, the count attacks Ventucci's halfwitted daughter; later, Ventucci kills him and drops his body in a sewer. Returning from the dueling place, Hughes finds that his wife has given premature birth to a child, and they are reconciled.