"Thunder Mountain" is the first of Tim Holt's 29 postwar westerns spread over the five year period from June, 1947 to June, 1952. While the film has one Zane Grey title, it has more elements in it from Grey's "To the Last Man" than from Grey's "Thunder Mountain", a not uncommon practice by RKO when dealing with the works of (Zane Grey). This one had Marvin Hayden(Tim Holt) returning to his Arizona ranch and finding it about to be sold for taxes. It has been in charge of his Mexican-Irish friend Chito Rafferty (Richard Martin). Local saloon-keeper Trimble Carson (Harry Woods), his friend Johnny Blue (Tom Keene) and Sheriff Bagley (Harry Harvey) have information that the ranch is to be the site of a dam and plot to obtain it. Plus, neighboring ranchers Ellen Jorth (Martha Hyer) and her brothers, Chick (Steve Brodie) and Lee (Robert Clarke), are antagonistic toward Hayden because of an old family feud between the Jorths and Haydens.