In the 10th film of the 66 Hopalong Cassidy movies, Russell Hayden makes his first (of 27 consecutive) appearances as Cassidy's sidekick/protégé "Lucky" Jenkins. The character's actual name in the many Clarence E. Mulford books that featured him was "Mesquite" Jenkins, and Hayden's role was billed in this film as Mesquite "Lucky" Jenkins, and this film was the first and last mention of Mesquite Jenkins. This initial pairing of the trio of William Boyd, Russell Hayden and George Hayes (who only became known as "Gabby" when he wasn't allowed by Paramount to carry his "Windy" moniker to Republic when he departed the Cassidy series, which makes any pre-1939 cast listing showing a credit listing for a George "Gabby" Hayes a misnomer and in error for those who don't care for revisionist film history) is the one that many western-film and/or Cassidy devotees consider the best of all the trio pairings in the series. This one finds the ranchers near a Wyoming Indian reservation suffering heavy losses because of cattle rustlers that leave signs that the Indians are the culprits. Hopalong Cassidy and his pals, Mesquite "Lucky" Jenkins and "Windy" Halliday buy the Bar Three ranch in the territory, and Cassidy suspects Andrews, the deputy government agent in charge of the reservation, of being the head of the rustlers. When Lone Eagle, a half-breed secretly working with the gang, is found murdered, Andrews incites the Indians to make war on the white men. Cassidy, as the leader of the ranchers, gains the confidence of the Indian chief by pointing out that Lone Eagle was "half-bad because he was half-white", and with the help of an Indian scout proves that Andrews killed Lone Eagle. The Indians then join forces with the ranchers in a Cassidy-led mounted charge against the rustler's stronghold, with the effective agitato score written by Lee Zahler for the earlier "Borderland" as the stirring background music.