Cowboy Jack Carter, the proud owner of the Australian shepherd Bunk, accepts the challenge of corralling 10,000 wild horses within a 10-day period. With the enormous sum for his efforts, Jack prepares to propose to Jessie Hayden. Unfortunately, Jack's rival, Charlie Champion, seeks to stop him from achieving both of his goals.
Carter Brace is out to murder Belden. Collins who was sent to bring in the border gang led by Brace, saves Belden's life in San Francisco. When they all reach the border, Brace tries again.
A Spanish-American boy raised by his Mexican servant, Clay Hill, Jr. vows vengeance on the three ranchers who murdered his parents.
