When the unscrupulous Carlos Manning discovers that an old Spanish land grant recently unearthed will leave a huge section of California real estate to the heirs of Don Quantero, he employs Mel Donovan and his killer henchmen to murder them all. That will leave Manning as the sole heir to millions. However, Delores Quantero tumbles to this plot and enlists the aide of two-fisted reporter, Cliff Roberts to save all her relatives.