The Traitor Within (1942)

Ambitious young truck driver Sam Starr is in love with Molly Betts, who shares with her father a resentment against John Scott Ryder,the town's Mayor. In WW I, Ryder took credit for an act of heroism performed by "Pop" Betts and all of Ryder's success since then has been the direct result of the hero-worship of the town's citizens---adulation which should have been extended to Betts. Shortly before his marriage to Molly, Sam takes Molly for a ride in his truck, the truck is sideswiped by another truck, and Sam's truck and its contents are demolished. Molly "imagines" the other truck carried the insignia of Ryder who operates a rival trucking line. Sam demands restitution from Ryder who, at first refuses, until Molly, unknown to Sam, tells Ryder she has uncovered evidence that proves Ryder was really a coward in the war, and not the hero he is thought to be. Ryder then buys Sam a new truck. A crooked politician,Al McGongile, also learns of this information and decides to shake-down Ryder for all the traffic can bear, He sets Sam up in a trucking business and blackmails Ryder, unknown to Sam, to turn over most of his most-profitable contracts. The Starrs become very affluent until, on their first wedding anniversary, Sam learns for the first time how unwittingly he has actually built his business upon blackmail and he leaves Molly. He goes to Ryder, reimburses him for the truck and berates him for the lack of courage to confess the truth about his war-time record. He berates him so much that Ryder, after Sam leaves, writes a confession and then shoots himself. Ryder's wife finds his body and the note...and destroys the note. And Sam Starr is charged with murdering Ryder, and a mob of angry citizens gather around the jail with intent to lynch.