Mexican renegade Don Carlos, wanted for espionage, poses as a horse buyer to obtain the prized "Black King". When owner Jim Riddle refuses to sell, Carlos arranges a race to win the horse by any means necessary. After a series of events, Bob Horton, accused of betrayal, escapes to Mexico and finds refuge with a surprising ally - the intelligent horse "Black King". Together, they outsmart the posse and ultimately expose Carlos' deceit, leading to his capture and Bob's vindication.
Riddle Ranch
A cunning gambler, Don Carlos, rigs a horse race to win a large sum of money, but his luck soon turns sour when he loses it all at the tables. In a fit of rage, he kills the dealer with a gun belonging to Horton, but Horton is subsequently arrested and struggles to prove his innocence.