Frontier Pony Express is a fast-paced Roy Rogers program western which could stand up on its own with any big-budgeted "A" picture. Per the title, Rogers plays an express rider, working the California-to-Kansas City route. While the Civil War rages in the East, our hero must contend with Yankee and Rebel forces who've encroached upon his home turf, both trying to win California over to their side. Meanwhile, businessman Lassiter (Edward Keane), ostensibly on the Confederate side, is actually a mercenary who hopes to play one army against the other so that he can move in and take over the territory himself. There's an awful lot of plot in this 58-minute oater, but Roy Rogers still finds time to serenade leading lady Mary Hart.