Episode 8 “Under the Cloak of War”
The Enterprise hosts Ambassador Dak’Rah, a Klingon general who defected to the Federation and is said to have killed his own officers when he learned that they had ordered attacks on civilians while fighting on the moon of J’Gal.
Veterans of the Federation–Klingon war, including Ortegas, M’Benga, and Chapel, are uncomfortable with his presence as they were there.
At last, Star Trek gets into some serious Sci-Fi and drama. Partially told in flashback. This examines the line between redemption and Revenge. Has the warlord truly changed. And how has the war changed some of the principle character.