Raiders Of San Joaquin finds Johnny Mack Brown, son of the railroad president doing a job of investigation. Rumors of trouble with railroad getting the right of way has brought Brown in incognito with friends Fuzzy Knight and the Jimmy Wakely Trio for musical interludes.
Tex Ritter and Jennifer Holt are the children of neighboring ranchers who are the last holdouts. When Ritter's father is killed he goes on a rampage.
The railroad's purchasing agent George Eldredge has gone into business on his own. And the one behind him is not the usual sort of villain one found in B westerns of the day.
And with two cowboy heroes it's not really clear who Jennifer Holt is going to wind up with. She's a winner either way.