Having botched the theft of notoriously dangerous racehorse El Diablo, gang leader Hank Canfield murders Ranger Elliott Norton while making his escape. Elliott's older brother Bob is hot on the trail of the outlaws, never suspecting the outwardly respectable Canfield of any involvement. The only living witness to the crime happens to be "Wild Boy," a mute orphan living with a band of untamed horses, including El Diablo. Norton doggedly attempts to coax the killer's identity from the silent boy, as Canfield and his men continue their quest to capture the valuable steed. Outnumbered and outgunned, Norton dodges danger through twelve death-defying chapters.Harry Carey starred in three Mascot serials, The Devil Horse being the last. Highly regarded asa silent-era cowboy hero, Carey easily made the transition to talkies. Throughout the 1930s, he continued to star in B-westerns while taking on supporting roles with the major studios, including his Oscar-nominated performance in Mr. Smith Goes To Washington.