The three men of the title in this superior B-Western are Hopalong Cassidy (William Boyd), Lucky Jenkins (Russell Hayden), and, making his series debut, grizzled old California Carlson (Andy Clyde). Carlson is the braggart cook of the Gardner outfit, a gang preying on defenseless ranchers, but when apprehended by Texas Ranger Hoppy, the old fool admits to having overstated his famous exploits. The bemused Hoppy takes California along to his namesake state, where Lucky is having a tough time bringing law and order to Santa Carmen, a community terrorized by greedy saloon proprietor Bruce Morgan (Morris Ankrum). Always the hothead, Lucky is determined to show Hoppy that he can handle things himself without any help. A bullet in the shoulder settles the matter once and for all, however, and the three work together to capture Morgan and his gang of cutthroats.