Hopalong Cassidy, a tough and experienced cowhand, leads a cattle drive from Texas up to Montana. As Hopalong and his crew guide their herd along the trail, they encounter various obstacles and threats, beginning with a gang of cattle thieves posing as legitimate "trail cutters." Then the herds ahead of Hopalong on the trail start to bunch up and slow down his progress. Two other ranch bosses, Gibson and Halliday, crowd Hopalong and try to take advantage of him. Can Hoppy save the day?