Watch Song of the Sierras for Free: How to Stream the Movie Online at 123Movies. . Jimmy Wakely wishes to sell to the government a group of wild mustangs which he has captured and trained for rancher Matt Blake. The competition is Flora Carter, the owner of a near-by ranch. The army colonel in charge decides to buy the winning horses of a cross-country race. Flora has her henchmen, led by Sam Phelps resort to foul means in order to try to win the race.