Prospector Juan Valdez is murdered by The Cactus Kid and his gang in an attempt to discover the location of his gold mine.

Valdez's dog Rinty witnesses the murder and can also lead the gang to the mine, making him the villain's target throughout the serial.

In addition Rinty must help Valdez's daughter Dolores legitimately find and claim the mine while being blamed for being the wolf that has been attacking local livestock.

The mysterious figure of Ramon is constantly on hand, overhearing pieces of the villain's conversations.

It is revealed in the finale of the serial that Ramon is in fact "Marco Roberto", an agent of the Justice Department.