John Gant (Audie Murphy), a notorious contract gunslinger, shows up in a sleepy Arizona town and refuses to leave. Grant's mere presence makes the townspeople uneasy. They realize that one man must be marked for death, but they don't know who the target is. The even-tempered town physician, Dr. Luke Canfield (Charles Drake), defends the mysterious assassin, but the other locals aren't so welcoming. They form a mob in an attempt to put Gant in the grave before finds the man he's looking for.