Captain Thorne places his motherless child in a boat and entrusts it to the waves when his ship founders at sea. The boat drifts ashore, and the child is found by a man, who rears it as sister to his own son. Reaching womanhood, the girl falls in love with a young secret service agent who is on the lookout for smugglers. She is persecuted by one Bill Hicks, a false friend of her brother, who is leader of the smugglers. The girl's adopted brother discovers in an old desk some papers which give a clue to his identity, and also bonds to the value of many thousand dollars. He incautiously takes his friend into his confidence, and is killed by the smuggler. The secret service agent, entering on the trail of the smuggler, is arrested for murder. His sweetheart contrives his escape from prison, and is waiting for him in a boat. The boat is picked up by a yacht, commanded by Captain Thorne. Hicks, fearing lest suspicion overtakes him, has left the village after the arrest of his rival, and after various adventures has become a member of the yacht's crew. Recognizing the castaways, he denounces them. The captain does not credit his story, and in a fit of revenge, prompted by mania, he sets fire to the yacht. The girl, locked in a cabin, is rescued by her lover, and they escape to a neighboring island. Hicks also succeeds in making his escape, and tries to kidnap the girl. Her screams bring rescuers, and while trying to escape Hicks is killed. The papers found on him are recognized by Captain Thorne and the girl, and through this documentary evidence father and daughter are reunited.