The Moonlighter

The Moonlighter is a 1953 3D Western film starring Barbara Stanwyck and Fred MacMurray.

Rela, his former sweetheart, is now involved with Wes younger brother Tom, who works in a bank. Tom has always admired Wes, who begins burning Princes ranch and killing some of Princes hands who lynched the innocent man.Tom is fired at the Rio Hondo bank by Mott, his boss. Cole Gardner, an outlaw, persuades Wes to rob the bank, and Tom decides to join them. Rela angrily warns Wes that if any harm comes to Tom, she will hold him responsible. ........

Source: Wikipedia