Wolves of the Rail.

Smoky Gap Railroad president Murray Lemantier is fed up with a bandit gang led by Buck Andrade constantly holding up his train and getting away with it. He hires ace detective David Cassidy to track down and get Buck, dead or alive. However, when Buck goes to see his dying mother she makes him promise to reform, and he does. Cassidy, though, doesn't care about that and tries to arrest him. Buck decides to do something that will once and for all show everyone that he has indeed reformed--especially Faith Lawson, a pretty station agent he's in love with.