John Sark is the owner of a piece of land coveted by Henry Murden, leader of the band of "White Riders," who has purloined the information that a railroad wishes to buy the property. Sark is a naturalist and has for an assistant Rose Ember. He discovers one of the rider's masks which is made of one of Rose's handkerchiefs, and this introduces a mysterious element into the love affair. The mask belonged to her father. The riders try to force Sark's hand, but are obliged to capture him. Rose, seeing Sark lead away, dons a mask and riding close to his horse, cuts his bonds. Sark kills Murden, and, finding that his savior was Rose, is once more happy in his love.