Death Rides a Horse is a western starring Lee Van Cliff and John Philip Law. John Philip Law plays Bill Meceita, a young man whose family is murdered right in front of his own eyes. Fifteen years go by, and Bill decides to seek revenge against his family's killers. He knows they are a gang, and he is determined to find them. Soon, Bill meets Ryan, played by Lee Van Cliff. Ryan is a skilled marksman, and he tells Bill that he is also seeking revenge, but he refuses to tell him why. Bill begins to figure out that Ryan actually knows something about the gang that killed Bill's family, but he refuses to tell him. The two men initially fight and disagree with one another a lot, but over time they begin to trust each other. Once they realize they are searching for the same gang, their relationship becomes very close.
Bill eventually figures out that Ryan is an ex-con. The four gang members who killed Bill's family also owe money to Ryan, and Ryan is determined to get it. The gang also managed to pin the blame for the rape and murder of Bills' family on Ryan, so Ryan was forced to complete a long prison sentence.
Ryan also thinks that Bill is crazy to devote his entire life to seeking revenge against his family's killer. He believes Bill focused on romantic relationships and building a life for himself. He begins to become sort of a surrogate father to Bill, giving him advice and encouraging him not to let his anger control him. In Ryan, Bill begins to see that he can seek justice for his family's killer, not just revenge, without letting his feelings control him.