3. Kirk between justice and vengeance
This may be one of the earliest, clearest “is Kirk going too far?” episodes. Old TV listings literally summarized it along the lines of Kirk walking a tightrope between retribution and justice, and the story leans into that.
Kirk lies to get the USS Enterprise sent to Karidian’s route, quietly investigates Leighton’s suspicions, and then pursues a man whose identity he cannot legally prove, based on trauma he carries from surviving Tarsus IV as a boy. One of those early jewels that fans still point out is the three-way sequence between Mr. Spock and Dr. McCoy, in which Spock is skeptical of Kirk's actions, and McCoy probes his motivations.
It becomes clear that his closest officers are concerned that he is seeking personal closure rather than just serving Starfleet's objectives. The episode doesn't provide Kirk with simple solutions, yet he never quite crosses the line into blatant retaliation. You may argue that he's doing the right thing or that he's perilously near to exploiting the Enterprise as a vehicle for personal reckoning because of that moral wobble, which keeps it interesting on replay.
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