The Lone Defender

The Lone Defender is a 1930 American PreCode Mascot movie serial starring Rin Tin Tin. This was Mascots first all sound serial the second to have any sound at all, after the partial sound in The King of the Kongo. This was Rin Tin Tins first serial at Mascot, after being dropped by Warner Bros. when they decided animal pictures would not work with Talkies. He also starred in the later serial The Lightning Warrior, which would be his last appearance. Mascot made a third serial, The Adventures of Rex and Rinty, but that Rin Tin Tin was not the same dog.

Prospector Juan Valdez is murdered by The Cactus Kid and his gang in an attempt to discover the location of his gold mine. Valdezs dog Rinty witnesses the murder and can also lead the gang to the mine, making him the villains target throughout the serial. In addition Rinty must help Valdezs daughter Dolores legitimately find and claim the mine while being blamed for the wolf attacking local livestock.The mysterious figure of Ramon is constantly on hand, overhearing pieces of the villains conversations. He appears to be another bandit but his actions seem to contradict that. ........

Source: Wikipedia