The Robert Hudson Pruit Company receives word from the Mayport distributors that the former’s recent shipments have not reached their destinations. The Mayport people are inclined to believe that a gang of river pirates is located along the route. In the employ of Judson is a rough individual by the name of Caesar who is really a secret agent of the pirates and who informs his chief of the dates of the shipments. Caesar becomes alarmed and returns to the gang, where his attentions to the chief’s niece, Zelma, are repulsed. Robert Judson, Jr., decides to locate the gang and sets forth alone. He meets Zelma, who is greatly impressed by the stranger, but while Robert endeavors to secure the information which will enable him to bring about the capture of the pirates, he is made a prisoner. Zelma’s attempts to liberate Robert are frustrated and Caesar, infuriated at the girl’s intercession in behalf of the prisoner, is about to deal severely with the young man when a pirate signals from a tree top that a heavily loaded steamboat is coming down the river. Immediate preparations are made to seize the cargo and Robert is left in the cabin securely bound. Alarmed at his son’s absence, Judson, Sr., has sent his shipment ahead under the guard of several armed men. The pirates meet with unexpected resistance and flee to the camp in panic. Caesar determines to make an end of his rival, but his desperate attempt is thwarted by Zelma and the outlaws are captured.