Thanya is a woman around whose presence there revolves an atmosphere of mystery. She is located in the Russian Capital, where she meets Vance Holden, an American artist. Although deeply in love with him, she is coquettish, and he, believing she is trifling with him, leaves her. Alexander Bagroff, Grand Duke of Russia, sees Thanya pass in her carriage and desires to know her. He arranges with a mutual friend to go to her apartment. He becomes infatuated with her but she dislikes him, not only because he is a man long past the prime of life, but for other and more important reasons. At midnight, after her guests depart, Thanya, in disguise, steals out to a small tavern where she meets Boris, her brother, leader of a club of social revolutionists. The gang is just about to choose a marked coin which will brand one as the man chosen to carry the next mission of death to a ruling power, in this case the most hated man in Russia, Bagroff. Boris draws the marked coin. Thanya falls in a swoon. In an agony of fear, she asks Boris to forsake his society. When he tells her it will be his pleasure to strike at the most hated man in Russia, the Grand Duke, Thanya is startled. Telling Boris of Bagroff’s infatuation for her, she promises to assist him in his mission. Thanya is invited to attend a ball given by Bagroff. She notifies Boris to strike that night at twelve. Boris gains admittance into the grounds, but is discovered near the house. A shot is fired, the guests are terrified. Thanya surmises the cause, she controls herself. Boris, cornered, attempts to gain admittance into the house and lose himself among the guests. As he enters he is shot. Bagroff, believing someone among his guests has betrayed him, orders his soldiers to tie Boris to a pillar, strip him to the waist and lash him with the Russian pronged whip. As the blood streams down Boris’ back, Thanya rushes to him, informing Bagroff that she is the traitor. They are both placed in a cell, where Bagroff offers Thanya her liberty if she will but become his mistress. He is rebuked, and both are sent with a train load of other prisoners to an exile in Siberia. During a storm, they escape and go to Paris. Vance, after leaving Russia, comes to Paris and here he and Thanya are brought together again, reconciled and married. Boris leaves for America. Vance encounters difficulties in selling his paintings. The following winter Bagroff comes to Paris. A Parisian doctor attending Vance, tells Thanya that he can bring her a client for Vance’s pictures. He brings Bagroff, who tells Thanya that through the Prince Kenla he can make all the people of Paris patronize Vance, providing she pay the price herself. Desperate to obtain the welfare of her husband, Thanya resolves to give herself to Bagroff for a night. The Princess sits for Vance. He becomes popular as if overnight. The Princess, going to a week-end party to the country, implores Vance to accompany her. Thanya remains alone in the city and unbeknown to Vance, prepares herself for the terrible ordeal with the Grand Duke. The appointment is made. Bagroff dismisses his servants, Thanya comes, disrobes. As he looks upon his prey with the lustiness he has nourished for years, he is suddenly seized by Boris, who, upon returning from America, learns of Bagroff’s presence there, and seeing his servants leave together, enters through a window in time to save Thanya. Pulling out his revolver, Boris makes short work of Bagroff, and immediately sets sail for America. The news of Bagroff’s mysterious death causes the Princess to hurry back to Paris, and Vance returns with her. He finds Thanya in his den, prostrated. He raises her up, but, as she had promised Boris, she tells him nothing of her night’s experience. Thanya and Vance open the window, and the sunlight pours into the room, an omen which prophesies a life of uninterrupted happiness for both of them in the future.