With the aid of his volatile stallion Rex and oil rigger Happy Cardigan (Harry Carey Sr.), young Jimmie Williams (Frankie Darro) tracks the Vanishing Legion, a gang that framed his father (Edward Hearn) for murder. Led by a mysterious criminal mastermind known only as "the Voice," the outlaws plan to sabotage a local oil operation. Boris Karloff provides the voice of the unseen villain in this classic serial co-starring Edwina Booth.
- The Last Frontier
- Cowboy Heroes of the Silver Screen
- Border Menace / Circle of Death
- Rough Riding Ranger
- Go Get 'Em Haines / 10 Laps to Go
- Roarin' Lead
- Come On, Cowboys!
- Heart of the Rockies
- Gunsmoke Ranch
- The Riders of the Whistling Skull
- The Painted Stallion
- Marshal of Gunsmoke / Oklahoma...
- Bad Man of Deadwood