Gillman returns to Porter after a four-day absence to find it held under siege by a gang en route to Mexico.
A pretty good, action-packed episode, bolstered by Nick Adams' performance as the leader of the gang holding the town at bay by holding Smith hostage in his own bar. Adams' character is such a mad dog, it almost makes the killer he played in the pilot to Wanted: Dead or Alive seem tame by comparison.
It's interesting that this episode clearly establishes Smith and Gillman as friends (something not particularly apparent in episodes like "Sunday's Child" or "Act of Vengeance"). There's also some continuity in this episode. Ralph is mentioned (even though we never see him), the doctor is the same doctor from "Terror" a few episodes back, and the bank president is played by Michael Fox, a role he reprises in the next episode, "The Threat." So this episode presages Star Trek Voyager in two ways.
The biggest problem with the episode are the two or three scenes where writer John Robinson virtually brands the episode an allegory for juvenile delinquency. "Oh, what drives youth to be this way," ask the Porter residents as the episode stops momentarily in its tracks. It's a small blessing Gillman didn't look out and ask the TV audience directly, so blatant was the messaging. Also, what happened to the rest of the gang that Adams' crew was waiting for, the 30-odd members who wrecked another town that the Rangers lost track of?
Speaking as someone who generally doesn't like hostage episodes, "Gang" was pretty good, although it would have been better without the heavy-handed moralizing on wayward youth.