Kirk finds a rogue starship captain meddling in a war between two peoples on Omega IV, a world whose history mirrors Earth's.
The Enterprise finds the starship Exeter abandoned in orbit around Omega IV, with only the captain, Ron Tracey, alive on the surface. Tracey has been interfering in a war between two peoples, the Kohms and the Yangs, and has broken the Prime Directive. Kirk must decide how to deal with him.
The episode shows a society that echoes the history of Earth and ends with a strong speech. It is often criticised for being heavy-handed, but it is notable for its use of a famous founding document as the centre of the plot, and for featuring a starship captain who has gone rogue.