A bandit has been impersonating the Lone Ranger, tarnishing his reputation as he robs and kills innocent people. The Lone Ranger is surprised when he is arrested by an old friend, the local sheriff.
When Don Pedro O'Sullivan tries to return to Mexico to battle an army colonel who is ruling his district according to his own whims, the petty dictator sends his henchmen to intercept and eliminate the aging gentleman. After thwarting one attempt on Don Pedro's life, the Lone Ranger and Tonto disguise themselves as the Don and his valet in order to lure the owlhoots into pursuing them instead. The two heroes succeed all to well, as the assassins capture them and the Don's daughter, and plan to have them all shot by a firing squad.