Fritz Lang puts Spencer Tracy through the ringer in Fury (1936) taking all control away from happy-go-lucky Spence before resurrecting him as a man of no conscience obsessed by vengeance.
As Depression era everyman Joe Wilson, Spencer Tracy has opportunity to show off all of his talents in what would really be his coming out at MGM. Joe is a good man made all the better by his love for Sylvia Sidney's Katherine Grant. At the start Wilson's sole obsession is working an honest job so he can save enough money to be married to Katherine. It's when he reaches this goal that his world comes crashing down.
Fritz Lang drains Wilson of his innocence by pinning a crime on him that he did not commit. He steers Tracy from disbelief through to horror by placing him in a jail cell, gathering a mob together and burning it down around him. What comes out of those ashes is ugly.
We like Joe Wilson at the beginning of Fury, and Tracy does such a tremendous job of bringing him to life that we still relate to him, or at least understand him, as he seeks to ruin an entire town.
By the same token the townsfolk, led by Bruce Cabot as Kirby Dawson, are given an ugly introduction, shown as bored gossips whose lives are so empty that they're plotting against Wilson while his arrest is still only rumor. This is the ugly part of community, where a common fear fuels hate and spurs action. As a mob they're animals, but later Lang isolates several of the worst offenders and we see monsters.
Sylvia Sidney's Katherine is the moral compass for Joe and, by the end of the film, the town. She's an accessory who has either made or kept Joe good through her own goodness. The mob, which blindly attacked Joe, is forced to witness the damage they've done to Katherine, and by Fury's end at least one of the accused begs her forgiveness.
Lang explores mob mentality in the first half of Fury, before tossing us a curve and setting the individual loose on the mob during the second half of the film.
Fury was nominated for an Academy Award for Best Original Story and snubbed for a few others including at least Best Director and Actor (though Tracy was nominated that year for San Francisco).