It turns out Kurn was staying with friends when Worf’s family was killed on Khitomer. Thought dead, he remained ignorant of his brother until he reached the age of ascension, at which point his adoptive parents explained the situation. Naturally, he decided not to do anything with this information for several years, until the Klingon High Council accused Mogh (his and Worf’s father) of aiding the Romulans during the attack on Khitomer that he and his wife died in.

As the elder son, Worf must now travel to Qo’noS to defend his father’s honour. Picard, apparently unbothered by the mockery that’s been made of the exchange program, agrees to ferry him. I guess no asteroid fields needed mapping this week. If Worf succeeds in challenging the ruling, his family’s honour will be restored. If he fails, he’ll be killed.

With Kurn acting as his bodyguard, Worf denies the charges against his father, while Duras, the child of Mogh’s most hated enemy, accuses Worf of being a disgrace. During a recess, Chancellor K’mpec tries to persuade Worf to drop the case. This makes Worf suspicious since (as he’s often demonstrated) Klingons are notoriously pernickety when it comes to matters of honour.

While the Enterprise crew try to prove what actually happened, Kurn receives a note asking him to meet the sender in a dark corridor with limited escape potential. When he gets there, Duras ambushes him and tried to turn him against Worf. When it doesn’t work, he gets some guys to stab him.

Luckily the wounds aren’t life-threatening, but Kurn can’t be Worf’s protector anymore. Worf asks Picard to do it, and while he tries to pass on the offer (perhaps noting what just happened to the last guy with the job) he ultimately can’t reject it. Which is lucky, because apparently the Enterprise has nothing better to do at the moment, so it’s not like he’s needed on the bridge.