Buzzy and the Phantom Pinto(1941)

Rancher Timothy Wade is ambushed by a masked man riding a pinto horse. His young son, Buzzy Wade and the loyal ranch foreman, Dude Bates, are mystified as to who anyone would kill Wade. But, Jim Dana, a U.S. government undercover agent, has his suspicions that the reason may have been in order to acquire the ranch from Buzzy and his older sister, Ruth. Dana thinks the ranch may have a large deposit of a mineral useful to a foreign country. His suspicions are confirmed when a couple of guys with heavy-accents show up inquiring about the property.