Susanna Pass

After finding a large oil bed underneath a lake, crooked engineer Del Roberts (Douglas Fowley) plots to take control of a fish hatchery run by Russell Masters (Lucien Littlefield), brother of Roberts' accomplice, Martin Masters (Robert Emmett Keane). Acting sheriff Roy (Roy Rogers) and his deputies square off against Roberts and his henchmen, and visiting female ichthyologist "Doc" Parker (Dale Evans) is caught in the crossfire between the opposing camps.