The Lone Defender is a 1930 American Pre-Code Mascot movie serial starring Rin Tin Tin. This was Mascot’s 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 Tin’s 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.

The plot revolves around Rin Tin Tin as “Rinty” and a secret gold mine fought over by the criminal “The Cactus Kid” and the legitimate owners. Material from this serial was edited into a feature film version and released under the same name in 1934.

Plot
Prospector Juan Valdez is murdered by The Cactus Kid and his gang in an attempt to discover the location of his gold mine. Valdez’s dog Rinty witnesses the murder and can also lead the gang to the mine, making him the villain’s target throughout the serial. In addition Rinty must help Valdez’s 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 villain’s conversations. He appears to be another bandit but his actions seem to contradict that.

It is revealed during the course of the serial that Ramon is in fact Marco Roberto, an agent of the Justice Department.

Cast
Rin Tin Tin as “Rinty”, Juan Valdez’s dog
Walter Miller as Marco Roberto, Justice Department Agent posing as the “Mysterious Figure”, Ramon
June Marlowe as Dolores Valdez, Juan Valdez’s daughter
Josef Swickard as Juan Valdez, Prospector who owns a secret gold mine
Buzz Barton as Buzz, Ramon’s sidekick
Lee Shumway as Amos Harkey, the villainous cantina owner
Julia Bejarano as Maria, the Dueña
Lafe McKee as Sheriff Billings
Arthur Morrison as Limpy
Frank Lanning as Burke, Prospector and Juan Valdez’s partner
Bob Kortman as Jenkins, one of the Cactus Kid’s Henchmen
Victor Metzetti as Red, one of the Cactus Kid’s Henchmen
Otto Metzetti as Red’s Partner