Lita Conway

In World War II, the Nazis require a special mineral, Compound X, discovered in Canada. Although intended to cure paralysis, the Nazis have discovered that it can be used in magnetic mines to destroy the British fleet and blockade America to prevent it assisting the Allies. The Mounties discover this plot and work to defeat and capture the Nazi spies sent to obtain the ore. (Wikipedia)

Someone is trying to kill Magpie Harper so he sends for the Range Busters. Crash and Dusty arrive to find him murdered. Then Alibi who was bringing the Range Busters' cattle drive money fails to show up. Dusty accidently finds a secret mine tunnel that leads to Alibi whom he sets free. Returning they see the murderer who flees but Crash is nearby to chase after him.

When Moreland's henchman attack Bob Horner the Range Busters break it up. Horner dies but they get the baby Moreland was after. He must have it to become it's guardian and take control of the Horner ranch. When the henchmen catch up with Alibi, they take the baby cradle not realizing Alibi has substituted his dummy Elmer. Crash having evidence Moreland is the one they want, now has a plan to expose him. (imdb)