Based on the title Zane Grey novel in name only, THUNDER MOUNTAIN is really a loose version of Grey's To the Last Man, which had already been made once in 1923 and again in 1933. Holt plays the returning son who arrives back at the homestead after college, only to find that an old family feud has been reignited. After a bit of digging, Holt discovers that the fighting is being provoked by a gang of ambitious crooks trying to drive the farmers off their land because the government intends to build a dam there and pay a high price for the rights. With the help of girl friend Hyer (who happens to be a daughter of the rival family), Holt exposes the crooks and reunites the clans. This western Romeo-and-Juliet tale was originally to have been released with the title of its real source, TO THE LAST MAN. Another film company had scheduled a feature named THE LAST MAN, however, so to avoid confusion the producer selected another title from author Grey's lengthy litany. He needn't have bothered; the competing film was never released.