Klingon ambassador K'Ehleyr (Suzie Plakson; my, she's tall) comes aboard the Enterprise, and she brings along with her a surprise for Worf: a young Klingon boy, Alexander, Worf's until-now-unknown-to-him son. She's also here on official business. A power struggle is imminent in the Klingon Empire between two rivals, Duras (Patrick Massett) and Gowron (Robert O'Reilly, making an instantly memorable impression with those crazy eyes) vying to become the next chancellor of the Klingon High Council. Failure to resolve the dispute could result in a civil war that could eventually sprawl well outside Klingon borders. K'Mpec (Charles Cooper), the dying chancellor, puts Picard in charge of the mediation and reveals that he has been poisoned by either Duras or Gowron in a gutless assassination for the power grab.
Like "Legacy," this is another example of TNG's standby, "two warring factions with the Enterprise as mediators," except this time it's done well. Whenever you involve the Klingons, there's an elevated, juicier flavor to the political intrigue and the mediation proceedings. Some scenes play like grand melodrama. And, of course, the way this all ties in with Worf raises the personal stakes. Worf selflessly accepting discommendation to save the Empire in "Sins of the Father" plays into matters here, with not only the Klingons shunning him at every turn, but the very notion that he cannot acknowledge his own son because the dishonor would be extended to him.
Then there's K'Ehleyr, the non-traditionalist call-it-how-I-see-it when it comes to the Klingon Empire, which plays in stark contrast to Worf's traditional values. I love K'Ehleyr's impatience with Klingon politics. When asked, "War over what?" she responds dryly, "The usual excuses: tradition, duty, honor." After a bombing on board a Klingon ship, evidence reveals a link with the Romulans, which means someone is involved in a conspiracy (although I wasn't quite sure what the bombing's goal was). K'Ehleyr starts poking into files to find the truth, discovers Duras is the conspirator, and in a shocking turn of events, Duras kills her.
Equally adrenaline-worthy is Worf going into full Klingon mode and throwing aside his Starfleet badge to claim his right for vengeance and battle Duras to the death. The themes of culture clash are in full force here, whether it's the conflict between being a Starfleet officer and taking Klingon vengeance rights (Picard reprimands Worf in a good scene), or the gulf between K'Ehleyr's human sensibilities and Worf's Klingon ways, or how it all ties into how Worf interacts with a son he doesn't know.