The Oregon Trail was the last of four serials that Johnny Mack Brown made for Universal in the 30's before making the switch exclusively to features. Jeff Scott (Johnny Mack Brown), a famous frontier scout, is hired by Washington officials to stop outlaw Indian raids on pioneer wagon trains crossing the rich fur regions of the Oregon Trail. Johnny Mack, the hero dressed all in black, leads the wagon train out west with his faithful sidekick Fuzzy Knight at his side. Together they battle the bad guys working for a big eastern syndicate who don't want the settles to disrupt their lucrative fur-trading activities.
Washington big-wigs hire on of the best frontier scouts to help them stop Indians from raiding the wagon trains crossing the famous Oregon Trail. Jeff Scott, the frontier scout joins the wagon train in disguise in order to gain evidence against the man he believes is responsible for the raids. This man just happens to the the wagon master so Jeff Scott must be careful.