Many of the other reviews do a great job of summarizing this excellent episode of one of the all-time classic television series. This is another John Meston tragic masterpiece that is as much Rod Serling or Alfred Hitchcock as a TV western.
Comparisons to Meston's "Phoebe Strunk" episode are appropriate. Denver Pyle's Ginness family "out nasties" Virginia Gregg's Strunk family. Whereas Phoebe Strunk seems to have some feeling for her family, the Ginness patriarch shows very little feeling for anyone other than himself. As a result, the Ginness boys show no compassion for anyone, even one another. When one of the boys is thrown from his horse and breaks his leg, the other brothers find it amusing. Toward the end of the episode, Matt delivers a short speech where he points out this attribute of the dastardly Ginness family.
I am fascinated with the casting of Denver Pyle as the Ginness patriarch. Pyle appears frequently on Gunsmoke - he was originally considered a candidate for the Matt Dillon character when the series was being cast. Pyle played another nasty character in the "Us Haggens" episode that first introduced the Festus Haggen character. Pyle plays Festus's uncle Black Jack Haggen in that episode.
I love the casting of Pyle in this episode because it contrasts perfectly with Pyle's casting as Briscoe Darling in The Andy Griffith Show. Here Pyle is the father of the wicked Ginness boys, while Darling is the patriarch of the similarly odd (but not evil) Darling family on TAGS.
The casting of this episode is perfect. Strother Martin's Will Timble character is as tragic a figure as you will find. The Ginness brothers are all familiar character actors of the time. Milburn Stone's Doc Adams is the closest thing to a hero as any character in the story. Burt Reynolds acts as Matt's sidekick in this episode, as he often did during his short involvement of the series. There is no sign of Dennis Weaver's Chester Goode character.
This is a great episode, and arguably my favorite of the entire series.