S18E13: Hostage!

The greatest bad-guy character actor of our time, William Smith, plays Jude Bonner, a bad guy who kidnaps, brutalizes, and shoots Miss Kitty in retaliation for his brother having been caught by Matt Dillon and hung for his crimes. Probably for the first time in seventeen years of Gunsmoke, Dillon takes off his marshal's badge before going after Bonner, with the intent of killing him.